Human Resource Practices, Eudaimonic Well-Being, and Creative Performance: The Mediating Role of Idiosyncratic Deals for Sustainable Human Resource Management

: Traditional Human Resource Management (HRM) focusing on maintaining the status quo is no longer in the spotlight. Sustainable HRM has become the new approach, emphasizing the need to attend to organizational results directed toward reaching di ﬀ erent goals and integrating the needs of diverse stakeholders. Moreover, in response to the challenges that organizations face in volatile, uncertain, complex, and ambiguous (VUCA) environments, Human Resource (HR) practices can contribute to the development of idiosyncratic deals (negotiation of individual HR practices) that might facilitate employees’ creativity and eudaimonic well-being in the long term and, thus, the sustainability of these organizations. Thus, the aim of this study is to test the mediating role of idiosyncratic deals (i-deals) in the unfolding relationship between HR practices, eudaimonic well-being and creative performance. Using a longitudinal database (three waves), the hypotheses are tested using structural equations modeling. The results support the idea that HR practices function as an antecedent for i-deals. More speciﬁcally, i-deals fully mediate the relationship between HR practices and eudaimonic well-being. In turn, i-deals and eudaimonic well-being fully mediate the relationship between HR practices and creative performance, which suggests that, through i-deals, HR practices become more beneﬁcial for both employees and employers. In conclusion, these results are important for sustainable HR development, because HR practices enhance i-deals, which increase well-being, enhancing performance in the long term.


Introduction
The knowledge-based economy and sustainable HRM are paving the way for a new type of human resources management where employees' task performance is no longer the only core result [1]. Research reveals the need to attend to other performance and well-being indicators that might contribute strongly to employees' sustainable development and organizational change, such as creative performance or eudaimonic well-being [2,3]. In a constantly changing environment with rapid work transformations, organizations need a competitive autonomous workforce capable of dealing with these new challenges and demands in a creative way. Therefore, the current environment is prompting organizations to adapt and be more flexible with their HR practices [4], and it is pushing employees to play a more active role in managing their own careers [5]. This situation has changed the nature and characteristics of their psychological contracts [6], and it has led to the development mechanism, based on the influence of the happy-productive worker thesis [28]. Even though these relationships may seem quite well-established, several authors have acknowledged that this question has not been fully resolved [29][30][31]. One way to extend this area of research is by considering other dimensions of performance and well-being that might be crucial in the development of organizations and individuals, such as eudaimonic well-being and creative performance. In fact, the consideration of these other types of outcomes may involve other mechanisms that link the different antecedents and outcomes in a more flexible, dynamic, and complex context. In this regard, idiosyncratic deals have been pointed out as a potential mechanism that may play a significant role in the impact of HR practices on promoting sustainable organizational and individual outcomes [32].
Idiosyncratic deals (i-deals) are personalized agreements that employees negotiate with their employers for their mutual benefit [32], aligning organizational practices with the needs and preferences of the employees. Through their HR practices, organizations may promote situations and work environments that increase the probability that these proactive behaviors will appear [33]. Thus, employees who perceive high-quality, professional HR practices in their organizations will have more resources and feel more motivated and capable of engaging in these negotiations. Additionally, research has shown the importance of i-deals in enhancing employment outcomes such as performance [34], employees' creativity [35], and well-being (e.g., personal growth) [36]. Nevertheless, their mediating role in the relationship between HR practices and employee outcomes has hardly been researched, specifically those outcomes more clearly oriented towards change and development.
Thus, the aim of this study is to test the mediating role of i-deals in the unfolding relationship between HR practices, eudaimonic well-being (one-year lagged), and creative performance (two-year lagged). Additionally, we will also test the mediating role of eudaimonic well-being in the relationship between HR practices and creative performance, extending the existing research on the happy-productive worker thesis to these constructs.

HR Practices, Employee Outcomes, and Their Operationalizations
During the 1990s, HRM research mainly followed a strategic management approach focusing on the relationship between HR practices and performance. First, performance was measured at the organizational level, but soon overall measures of individual performance were also considered [19][20][21]. Moving toward a more encompassing approach, some academics have pointed out the need to incorporate the effect of HR practices on employees' well-being as an outcome in itself [18]. In fact, the relationships between HR practices and both types of employee outcomes (performance and well-being) have generally been found to be positive, thus supporting an "optimistic perspective" [37], because traditional practices lead to higher performance and well-being. Moreover, the path from well-being to performance has mainly received research attention from the perspective of the Happy-Productive Worker model [28].
However, one of the main problems in HRM research is the lack of unique definitions and operationalizations of performance and well-being [38]. In fact, Van de Voorde and colleagues' review of quantitative studies [7] showed the diversity in the operationalizations of performance (e.g., operational or financial) and well-being (e.g., happiness, health-related, or relationship well-being). These operationalizations are quite important because they can lead to different relationships with HR practices [7,18] and to different conceptualizations about sustainability. Performance or well-being facets other than those traditionally used could provide greater insight into organizational needs in the current competitive, turbulent, and changing world. Today, employees are expected to be more and more autonomous, proactive, and able to adapt their resources to face problems and grow. In this regard, eudaimonic well-being and creative performance are more necessary than ever, and we need to consider both to better understand how HR practices can contribute to enhancing these outcomes. Thus, there is a need to examine the relationships between HR practices, creative performance, and eudaimonic well-being by extending the research on this issue beyond the mainstream conceptualizations of job satisfaction and task performance.

Well-Being at Work
The definition and operationalization of well-being is a complex endeavor [39]. Two long traditions can be differentiated in the study of happiness and well-being: the hedonic and the eudaimonic approaches. The hedonic conceptualization focuses on maximizing pleasure, experiencing positive affect, and reducing or escaping from pain [40]. The eudaimonic approach focuses on individuals' development and self-realization [41], understood as growth and human fulfilment. Different authors included both components in their definitions and classifications of well-being. For instance, Cropanzano and Wright [42] defined the concept of well-being at work in four ways: as job satisfaction, as the profile of positive and negative affect, as the lack of emotional exhaustion, and as psychological well-being. The first three definitions refer to hedonic well-being, whereas the latter refers to eudaimonic facets. The eudaimonic conceptualization of well-being considers the individual choices employees make to achieve greater accomplishment and meaning [43], and it is related to positive psychology [44]. Hence, eudaimonic well-being attempts to achieve positive personal traits, such as self-determination, talent and creativity, vocation, or perseverance [44], which are especially pursued in organizations to attain competitive advantage as well as sustainable HR development [3]. HR practices can foster eudaimonic well-being to the degree that they provide a trusting and empowering environment that allows employees to engage in personal growth and development. For example, to the extent that organizations offer possibilities for training, feedback on performance, and flexibility in work arrangements, employees would be expected to grow professionally. Hedonic well-being has a short-term perspective, whereas eudaimonic well-being focuses on long-term well-being, aiming for employees' full potential [45].
Taking this into account, and considering the sustainable HRM approach, proper HR practices will induce and promote employees' eudaimonic well-being. The literature focusing on eudaimonic well-being has mainly operationalized it as engagement e.g., [43] and, to a lesser extent, as involvement, meaning of work, or flourishing e.g., [46]. For instance, Alfes and colleagues [47] made one of the first attempts to link perceived HR practices and engagement, finding a regression coefficient of 0.31 (p < 0.01). Later on, research has found engagement to be positively related to systems of practices promoting employees' voice [48,49]. Research has also found high-performing HR practices to be positively related to engagement and, in turn, to in-role performance [50]. However, there is an ongoing debate about the appropriateness of engagement as a measure of well-being or as a proxy for performance as in [51]. In this sense, it has been pointed out that, when eudaimonic well-being is measured as engagement, it involves a certain performance component (or organizational success), rather than focusing on the employees and their growth. Therefore, there is a need to consider other eudaimonic variables that can be more related to sustainability and long-term well-being. To date, few articles have taken other eudaimonic variables into consideration, such as purpose in life or personal growth, which are more related to the self-development definition of eudaimonia [41] and, in the long term, sustainability. Thus, in order to advance the understanding of the relationship between HR practices and well-being, different components of eudaimonic well-being must be incorporated. Furthermore, there is a lack of research considering simultaneously the relationship between HR practices, eudaimonic well-being and creative performance. This prevents the advancement in our knowledge about the sustainability of systems of HR practices.

Performance
Since Huselid's [17] seminal work, organizational performance has been the focus of research examining the impact of HR policies and practices. The rationale for this relationship is based on theories such as social exchange [52], the norm of reciprocity [53], or signaling theories [54]. In this regard, it is assumed that employees perceive HR practices as an investment and recognition from the organization. Therefore, they respond with positive attitudes and behaviors [55], thus enhancing performance. Moreover, HR practices are tools to improve the skills and abilities that allow employees to perform better. Thus, the basic idea is that HR practices influence organizational performance through their effects on individual performance. Therefore, research has claimed that, in order to understand the mechanisms between HR practices and organizational performance, we first need to understand the impact on individual performance and employees' attitudes and behaviors towards work [56]. Different dimensions of individual performance have been identified, namely, task performance, contextual performance, adaptive or creative performance, and counterproductive work behaviors [22]. More attention has been paid to task performance [57] and, to some extent, contextual performance [58]. However, there are fewer research studies on counterproductive measures [59], and even fewer on creative performance [60]. Recently, some attention has been paid to exploring the impact of high-performance work systems on employee creativity [61], although the underlying mechanisms and the boundary conditions are far from being clearly identified and understood [3].
Creative performance is an important outcome for sustainable organizations. As the organizational environment becomes more turbulent and unpredictable, organizations need to promote employees' creativity so that they can oversee and improve their own work [62]. Robots will be taking over most of the repetitive tasks in organizations, but creativity is inherent in humans, and organizations need to foment it through their HR practices. In fact, it has been stated that creativity is critical for organizational growth [63], long-term survival, and organizational success [64]. It is also necessary to compete in an increasingly dynamic marketplace [62] in a way that should help to achieve greater sustainability. Creative performance might be defined as the generation of novel and useful ideas [65] that can be important for innovation and competitiveness in changing environments e.g., [66].
Moreover, creativity and innovation that occur inside the organization remain in the organization, at least in the short-to mid-term, achieving a competitive advantage [67]. According to the resource-based view (RBV) [68], organizations provide HR practices to their employees so that they can become a source of competitive advantage over other organizations. HR practices can increase creative performance because they enhance motivation and willingness to make discretionary efforts [69]. When HR practices are perceived as an investment in employees, employees can use their skills and capabilities to engage in creativity [70]. However, as Gupta [71] reported, the relationship between HR practices and creativity has received little attention, and the studies focusing on this relationship have failed to provide a coherent directionality between these two variables. Therefore, more longitudinal studies with these variables are needed. Our study aims to contribute to filling this gap in the literature.
In sum, we propose that HR practices might contribute to the development of certain aspects of well-being and performance that are essential in coping with the changing and turbulent environments faced by today's organizations. Thus, it is critical to enhance eudaimonic well-being and creative performance, and we need to better understand the relationships between HR practices and these two variables. Therefore, the following hypotheses were formulated:

Mechanisms Linking HR Practices, Eudaimonic Well-Being, and Creative Performance: The Role of I-Deals
It is important to understand the mechanisms linking HR practices and outcomes, because it is still unknown how HR practices translate into competitive success [72]. By improving our knowledge of these mechanisms, we can better understand how to optimize organizational environments to achieve greater performance and well-being.
An important part of the research on the mechanisms between HR practices and performance has focused on the mediating role of well-being. This approach was motivated by the happy-productive worker thesis [28], which states that, ceteris paribus, a happy employee is a productive one. This theoretical background has generated a large number of scientific articles focusing on the mediator role of hedonic well-being, mainly job satisfaction, in the relationship between HR practices and performance [7,31]. However, HR practices might also increase performance by increasing eudaimonic well-being. When organizations offer positive HR practices, such as training or information about individual performance, employees might experience a sense of work significance, personal growth, or self-fulfillment, which in turn might increase their contributions to the organization. Thus, considering the mediator role of eudaimonic well-being in this relationship creates an opportunity in the HRM field to complement the scarce empirical evidence available on this issue e.g., [47,73], especially in the case of creative performance, because it requires a more proactive and dynamic component than task performance. The use of creative performance means that the employee exceeds what is expected from him/her to surpass the limits of compliance. Thus, it is important to consider eudaimonic well-being, which is closely related to self-development and growth, as a variable that can predict and enhance creative performance.
Khoreva and Wechtler [73], for instance, found that psychological or eudaimonic well-being mediated the relationship between HR practices and innovative performance, whereas physical and social well-being mediated the relationship between HR practices and in-role performance. That is, eudaimonic well-being is related to an energetic connection with the job itself [74]. In fact, employees with higher eudaimonic well-being (such as engagement) are found to be more creative and productive [75]. Based on the above, the following hypothesis was formulated:

Hypothesis 3 (H3):
Eudaimonic well-being mediates the relationship between HR practices and creative performance.
Nevertheless, the portrayal of eudaimonic well-being and creative performance needs further development in terms of the mechanisms between HR practices and these outcomes. Eudaimonic well-being and creative performance are two types of outcomes that are highly related to the active pursuit of change and development [76,77]. In this pursuit, proactive individual behaviors play an important role because they foster change-oriented behaviors [78,79]. Moreover, proactive behaviors are seen as a key to successful organizational achievement [80]. In fact, employees who engage in proactive behaviors challenge the status quo rather than just accepting the established work conditions [10], and this willingness motivates workers to show more creative performance or have a meaningful purpose in life and a commitment to grow professionally. That is, they do not agree with the conditions as they are.
Previous research has considered the perceptions of HR practices to be an antecedent of employees' proactive behaviors [81]. Therefore, we consider that HR practices will have a positive effect on well-being and performance through the enactment of proactive behaviors such as i-deals. In this regard, the consideration of i-deals incorporates the active role of employees in the HRM process. The worker is no longer considered a passive recipient of HR policies and practices. In fact, static HRM may be suitable in stable contexts, but in dynamic conditions, this paradigm is no longer adequate, due to the need for more flexibility and dynamic adjustment of HR practices [82].
I-deals are defined as "voluntary, personalized agreements of a nonstandard nature that individual employees negotiate with their employers regarding terms that benefit them both" [8,29]. I-deals, therefore, advocate for a win-win situation in organizations, which induces well-being, builds a stronger relationship between the employee and the organization, and fosters a cooperative orientation that also encourages creativity, because mutual beneficial conditions have to appear [83]. In other words, when employee and employer are looking for mutual benefits and conditions that are favorable to both, creativity can be enhanced.
I-deals are usually initiated by employees in order to achieve a better fit between their work and their expectations and needs [84]. Employees who are aware of the knowledge, resources, and skills provided by the organization (in this case, through HR practices) have a greater predisposition to negotiating and crafting these practices, using a bottom-up approach [85]. Thus, they might contribute to their performance and well-being through the adjustment of job conditions. Employees who enroll in i-deals have been found to build their careers better and achieve longer and more sustainable careers than employees who do not [86].
Previous research has acknowledged the important role of organizations in providing situations and designing environments that allow employees to develop proactive behaviors [33]. However, research on i-deal antecedents has usually focused on individual factors [87][88][89]. Thus, recent literature has pointed out the need to pay attention to organizational antecedents of i-deals, such as HR practices [90].
Professionalized HR practices offer a context where individuals can develop personalized arrangements. In order to negotiate an i-deal, an employee needs to have a solid package of HR practices to negotiate with their employer. Moreover, current work conditions are leading organizations to suit and craft HR practices to employees' needs and preferences. In fact, although the literature is infrequent, some recent theoretical articles insist on the importance of HR practices in developing i-deals [91][92][93]. Rosen and colleagues [88] acknowledge that different types of HR practices can lead to different levels of negotiation for individual arrangements. More precisely, they found that some practices lead more easily to individual negotiations than others [88]. Thus, some practices, such as training, rewards, or performance appraisals, promote negotiations between employees and employers more, or at least they have been studied more than other types of practices [33,92].
HR practices could influence the enactment of proactive behaviors and, more specifically, i-deals, through different processes [33]. For instance, HR practices enhance employees' skills, motivation and/or opportunities (following the AMO-abilities, motivation and opportunities-model). If an employee feels more capable or motivated at work, s/he can feel empowered to engage in introducing flexibilization in their employee-employer relationship, through i-deals [94]. Furthermore, HR practices provide employees with resources such as growth, recognition, or empowerment [71], which can make them feel engaged and involved in proactive behaviors and attitudes towards work [95]. Additionally, empowerment can contribute to employees' willingness to customize their work arrangements, leading to more i-deals [96].
Previous research suggests that HR practices lead to i-deals through the enhancement of employees' autonomy [97]. Autonomy increases the internal control of employees [98], which may induce a negotiation with their employers. Security practices can also enhance autonomy, providing stability and reducing threats to control [99]. In situations where the worker has the right conditions to develop greater autonomy, s/he will be more likely to introduce new ideas or procedures, taking initiative and negotiating or modifying their workplace conditions [33].
Furthermore, HR practices are known to enhance employees' commitment [97], which, at the same time, can increase the appearance of i-deals [93]. Furthermore, HR practices may motivate employees to go beyond what their job duties require [85], increasing their willingness to engage in negotiating i-deals.
Research has also found that i-deals can contribute to different employee outcomes. In fact, Liao, Wayne, and Rousseau [90] proposed a framework where i-deals could influence well-being measures, such as job satisfaction or engagement, and performance measures, such as organizational citizenship behavior (OCB), turnover intentions, or creativity. Moreover, proactive employees are found to be more engaged in creativity and innovation because they look for improvements in their current work conditions [100]. Recent research has acknowledged the importance of better understanding the process that leads to creative performance by making the employee more engaged, motivated, and committed to their job [101]. Hence, providing practices and a work environment that motivate the employee to change things at work (which leads to i-deals) can be a solution to enhance employees' creativity and, thus, respond to the new organizational demands. Previous research has found that motivation is a key to creativity [66,69]. These proactive behaviors allow employees to be innovative and adapt to workforce changes and, thus, improve their creative performance. Employees with proactive behaviors are more engaged in creating new ideas because they are constantly looking for a better situation at work [69]. Therefore, i-deals are expected to have a positive relationship with creativity [102]. Hence, the following hypothesis was formulated: Hypothesis 4 (H4): I-deals mediate the relationship between HR practices and creative performance.
Previous research on proactive behaviors has acknowledged their effect on well-being [36]. More specifically, i-deals fulfil employees' need to adapt HR practices to their necessities, increasing their well-being [103]. Research on i-deals and well-being has mainly focused on job satisfaction as in [90]. However, the foundation of i-deals, based on being engaged and grounded in a strong conviction to improve things at work, makes it plausible that this proactive behavior could also influence eudaimonic well-being.
The literature on the relationship between i-deals and eudaimonic well-being is still insufficient. Although a few studies have focused on other variables, such as professional development [104] or career success [105], which are related to the full-functioning aspect of the eudaimonia concept, the majority have used engagement as in [106]. However, this follows the HRM tradition of focusing on performance because engagement is more related to willingness to work and can be used as a proxy for performance, as explained above. For real employee sustainability in organizations, taking into account their performance, but also their well-being, development, and growth in the long term, researchers have acknowledged the importance of incorporating not only job-related variables, but also context-free ones [107], such as purpose in life or personal growth.
In general, i-deals may be an important variable to explain the relationship between HR practices, performance and well-being, because it considers the goals and needs of employees [93] and organizations in a win-win situation. Thus, we formulated the following hypothesis: Hypothesis 5 (H5): I-deals mediate the relationship between HR practices and eudaimonic well-being.

Procedure
Organizations were contacted by the members of the research group and asked to participate in the study. Convenience sampling was used, attempting to achieve a heterogeneous sample by including companies from different sectors in different Spanish locations. Thus, we contacted organizations from different sectors (production, financial services, education, public services, social work, etc.) using different networks of relationships (research networks, consultancy firms, organizations participating in the study). Firm managers or HR managers were contacted first to ask if they were willing to have their companies participate in the research. An initial meeting was arranged to provide information about the procedure, the time required, and the goals of the project. After receiving managements' consent, we invited all the employees in the organizations to participate by filling out a questionnaire voluntarily and confidentially. Respondents filled out the questionnaire at two additional timepoints, separated by periods of nine months to one year.

Participants
We obtained measurements from 1647 employees from 42 organizations at the first data collection timepoint (T1). The mortality of the sample reduced the answers of employees to 792 employees from 24 organizations (from these 42) at the second timepoint (T2), and 395 employees at the third timepoint (T3) from nine of the 42 organizations surveyed at the first data collection timepoint. The sample is still diverse in terms of different characteristics such as economic sectors (financial services, production, education, health and social) organizational type (private, public and social), and organizational size.
The three samples (T1, T2, and T3) were matched by using a specific self-generated code to ensure that the subjects' answers, although anonymous at T1, T2, and T3, were correctly matched. The three data waves consisted of 209 employees who answered questionnaires at timepoints 1, 2 and 3. The majority of those 209 employees worked in the services sector (80.4%), and the rest (19.6%) in the secondary sector (mainly in the manufacturing industry). Slightly more than half of the sample was composed of females (60.8%). The majority of the participants were between 35 and 50 years old (56.5%), followed by employees under 35 years old (38.3%) and those over 50 years old (5.3%). Tenure in the company included more than 5 years (71.4%), from 1 to 5 years (20.6%), and less than 1 year (8%). Finally, most of the sample were full-time employees (82.1%), and the rest (17.9%) held part-time jobs.

Measures in T1
HR practices scale: we used 24 items to assess eight HR practices, based on the previous work of Boon, den Hartog, Boselie and Paauwe [14], and previously validated in Spanish [108]-training and development, contingent pay and rewards, performance appraisal, recruitment and selection, competitive salary, work-life balance, employment security, and exit management.
The question presented to the employees was, "my organization offers me . . . " for each of the HR practices. The wording of every practice referred to clearly stated that the HR practice in the company was implemented in a professional way. The response scale was a five-point Likert scale ranging from 1 (not at all) to 5 (a lot). An example of an item is: " . . . the opportunity to develop new skills and knowledge for my current job, or for possible future positions".

Measures in T2
I-deals: An ad-hoc questionnaire with nine items was used to measure the i-deals related to the HR practices [109]. The response scale was a five-point Likert scale ranging from 1 (never) to 5 (always). An example of an item is: "I negotiate with the organization about my opportunities for training and promotion".
Eudaimonic well-being: Eudaimonic well-being was measured with the purpose in life and personal growth scales from Ryff's measure [41], with a total of 11 items. The seven-point Likert response scale ranged from 1 (strongly disagree) to 7 (strongly agree). An example of an item is: "for me, life has been a continuous process of learning, changing, and growth".

Measures in T3
Creative performance: Creative performance was self-assessed with the three items on the scale by Oldham and Cummings [110]. The response scale was a seven-point Likert scale ranging from 1 (not at all) to 7 (to a large extent). An example of an item is: "I am practical at my job and propose useful ideas for my organization".

Analyses and Hypothesized Model
Descriptive statistics, correlations, and Cronbach's alphas were calculated with IBM SPSS Statistic 24. In order to test the mediator effect of i-deals in the relationship between HR practices, well-being, and performance, we used structural equation modeling (SEM) with AMOS (version 24). To calculate the significance of the indirect effects, we used Monte Carlo confidence intervals, as recommended by [111].
Our hypothesized model considered the direct and mediated effects of HR practices on employee outcomes (see Figure 1).

Results
Means, standard deviations, and correlations among variables are shown in Table 1. Cronbach's alphas of all measures were satisfactory. Positive relationships were found between HR practices, ideals and eudaimonic well-being, and between i-deals and eudaimonic well-being and creative performance.  [112]. Results from the structural equation model can be seen in Figure  2. In general terms, the model shows support to our main hypothesis and shows a positive relationship of HR practices with creative performance and eudaimonic well-being through i-deals and over time.

Results
Means, standard deviations, and correlations among variables are shown in Table 1. Cronbach's alphas of all measures were satisfactory. Positive relationships were found between HR practices, i-deals and eudaimonic well-being, and between i-deals and eudaimonic well-being and creative performance.  [112]. Results from the structural equation model can be seen in Figure 2. In general terms, the model shows support to our main hypothesis and shows a positive relationship of HR practices with creative performance and eudaimonic well-being through i-deals and over time.

Results
Means, standard deviations, and correlations among variables are shown in Table 1. Cronbach's alphas of all measures were satisfactory. Positive relationships were found between HR practices, ideals and eudaimonic well-being, and between i-deals and eudaimonic well-being and creative performance.  [112]. Results from the structural equation model can be seen in Figure  2. In general terms, the model shows support to our main hypothesis and shows a positive relationship of HR practices with creative performance and eudaimonic well-being through i-deals and over time.  Hypothesis 1 stated that HR practices would have a positive effect on eudaimonic well-being. As the results show, indirect effects were found between HR practices and eudaimonic well-being, through i-deals, supporting this hypothesis. Hypothesis 2 stated that HR practices would have a positive effect on creative performance. We found support for this hypothesis through a double mechanism: i-deals and eudaimonic well-being.
Hypothesis 3 stated that eudaimonic well-being would mediate the relationship between HR practices and creative performance. This hypothesis was partially supported because eudaimonic well-being mediated the relationship between HR practices and creative performance, but only when HR practices had an effect on i-deals.
Hypothesis 4 stated that i-deals would mediate the relationship between HR practices and creative performance. This was partially confirmed as well. Specifically, i-deals significantly mediated the relationship between HR practices and creative performance, but only through the effect of eudaimonic well-being. The indirect double effect of HR practices on creative performance was significant as the lower bound (LB) and upper bound (UP) show (LB = 0.10; UB = 0.92).
Finally, Hypothesis 5 stated that i-deals would mediate the relationship between HR practices and eudaimonic well-being. This was confirmed because i-deals fully mediated the relationship between HR practices and eudaimonic well-being. Moreover, the indirect effect of HR practices on eudaimonic well-being through i-deals was positively significant (LB = 0.09; UB = 0.60).
Although not hypothesized, eudaimonic well-being also mediated the relationship between i-deals and creative performance. This indirect effect was also found to be positively significant (LB = 0.21; UB = 1.06).
In sum, we found three fully mediated relationships (HR practices → i-deals → eudaimonic well-being; i-deals → eudaimonic well-being → creative performance; HR practices → i-deals → eudaimonic well-being → creative performance as a double mediation), with all the indirect effects found to be significant. Thus, our results found support for i-deals as a mechanism mediating the relationship between HR practices and relevant outcomes for organizational sustainability over time. Results show that, when HR practices contribute to the development of personal deals between the individual and the organization, personal growth and creative performance are promoted.

Discussion
The aim of this study was to test the mediating role of i-deals in the relationship between HR practices and two lagged employee outcomes: eudaimonic well-being and creative performance. Moreover, we wanted to test the mediating role of eudaimonic well-being in the relationship between HR practices and creative performance.
The results contribute to the HRM literature by extending the analysis of the relationship between HR practices, well-being, and performance, using constructs and operationalizations that have received limited research attention, even though they are becoming crucial in better understanding the development of personal and organizational change: creative performance and eudaimonic well-being. Our results show HR practices to be relevant over time for the development of employees with higher levels of eudaimonic well-being and creative performance. Both outcomes are crucial factors for organizations operating in turbulent environments and competing for human talent. In this regard, we contribute to the literature on sustainable HRM by showing the contribution of HR practices to performance and well-being indicators that are strongly related to sustainability. Moreover, our study contributes to the disentanglement of the black box between HR practices and employee outcomes by showing the mediator role of idiosyncratic deals in this relationship and the mediator role of eudaimonic well-being in the relationship between HR practices and creative performance. In addition, based on the sustainable HRM approach, our study considers different organizational goals (performance and well-being) and uses three data waves with about 9-12 months between them to show the mid-term influence of these HR practices. Our results have several implications for theory and practice that require further consideration.

The Effects of HR Practices on Employee Outcomes
Our results show that HR practices have a positive indirect effect on employee outcomes. This finding is consistent with the mainstream research on HRM, which states that HR practices have a positive impact on performance and well-being [19][20][21]. Although in this study the direct effect was not significant, the mediation through i-deals (and eudaimonic well-being) helped to build a path between HR practices and eudaimonic well-being and creative performance.
Sustainable HRM considers the expectations of different stakeholders in the organization [113], and, therefore, HR practices need to consider employers', employees', and customers' goals. Thus, organizations need to focus on enhancing their employees' performance in order to provide good service to customers and ensure productivity, while enhancing employees' well-being in the long term [114]. Moreover, it is important to focus on results that might allow organizations and individuals to deal with a turbulent and changing environment that requires high doses of creativity. At the same time, personal growth and sense of purpose provide measures that depart from a static view of well-being in organizations and inform about the positive development of employees' self-fulfillment. The results of our study show that employees' growth and creative performance are related to HR practices when employees have the opportunity to adapt those practices to their own needs.
HRM research has usually operationalized performance as global, task, or contextual. New challenges and changes in organizational environments [66] have made it necessary to focus on other types of performance to achieve a competitive advantage [67]. In this regard, the literature has defended the need to focus on creative performance [62] as a critical variable in long-term survival and organizational success [64]. Our results contribute to broadening the scope of this research by showing that HR practices are beneficial for this type of performance, through the enhancement of i-deals and well-being.
In the same way, the analysis of the relationship between HR practices and eudaimonic well-being is also an important contribution of this research. Research on HRM has traditionally operationalized well-being in hedonic and static terms, normally as job satisfaction [42]. However, due to new challenges and requirements from organizations, research on eudaimonic well-being emerged after the financial crisis of 2007 [51,73]. This type of well-being is more focused on employees' self-realization [41] as they actively pursue change and development [76,77]. Previous research on the relationship between HR practices and eudaimonic well-being has mainly operationalized it as engagement as in [43]. Our results show that HR practices also contribute to the development of eudaimonic well-being, operationalized as personal growth and purpose in life. Moreover, it explains the mechanism through which this influence is achieved, the development of i-deals over time.
Thus, the use of different operationalizations of well-being and performance gives us a new approach to a sustainable long-term HRM that considers employees' needs and is framed in the context of greater competitiveness and rapid changes, leading to new approaches in the research on HRM. First, eudaimonic well-being takes long-term well-being into consideration for real sustainability, by taking into account employees' development and full potential. Second, creative performance is a key variable in rapidly changing environments. Employees need to be more flexible and resolute in ways that surpass what is expected in their daily job. In this way, organizations will achieve competitive advantage through their employees [68]. Therefore, both variables go beyond the status quo in traditional HRM research, opening up a wide spectrum of unanswered research questions and providing some useful answers in this endeavor. This study provides empirical evidence for the mutual gains perspective [27], specifically for strong mutual gains [115], where well-being is positively influenced by HR practices (in our case, through i-deals) and also influences performance. Thus, our results also support theoretical models such as social exchange that propose HR practice to increase both types of outcomes [52]. However, we found non-significant direct relationships; that is, HR practices have a positive effect on creative performance through employees' behaviors when looking for i-deals and, in turn, when experiencing eudaimonic well-being. These results highlight the importance of understanding the mechanisms in this relationship.
Finally, the use of three data waves allowed us to capture the effects of HR practices and the outcomes considered over time, showing a long-term effect of HR practices on eudaimonic well-being and creative performance. HR practices enhanced eudaimonic well-being one year later (through the enhancement of i-deals), and the increased level of eudaimonic well-being boosted creative performance the following year. This responds to the previous literature asking for longitudinal research on sustainable HRM, and it shows the long-term effects of HR practices.

The Mediating Role of I-Deals
Our results showed that i-deals mediated the relationship between HR practices, eudaimonic well-being and creative performance. HR practices, such as training and development or contingent rewards, are more prone to considering the aspirations of employees [32,88], and so they can have a greater effect on the appearance of i-deals, and were found to have a positive effect on well-being and performance by increasing employees' capacity to negotiate their HR practices. Therefore, this work also provides evidence that helps to understand the organizational antecedents of i-deals beyond employees' personal characteristics [90].
This result supports research suggesting that i-deals can be promoted by the organizational context through different actions. Thus, employees' perceptions that organizations provide them with HR practices that enhance their capabilities at work and their willingness to progress in the workplace were found to be positively related to their proactive behaviors [33]. In this sense, we broadened the view of i-deal's antecedents, which have mainly been considered as personal factors, by showing the important role of organizational factors. These results support the view that by increasing employees' levels of motivation, autonomy, or engagement [33,90,97], HR practices influence individualized negotiations and improvements in these practices. In turn, employees engaged in i-deals who showed dynamic capabilities and change-oriented behaviors were found to have higher levels of eudaimonic well-being and creative performance [79]. These results also support the consideration of i-deals as personalized agreements that benefit both the employer and the employee, because they enhance creativity [11,32] and employees' self-development [86], and, thus, the sustainability of the organizational system. Moreover, when employees are more innovative and search for improvements in a changing work environment, they can be a source of competitive advantage [68].
The results also offer support for the indirect mediating role of i-deals in the relationship between HR practices and creative performance through the enhancement of well-being. In more professionalized HR environments, i-deals appear to be a mechanism for employees to adapt the organizational practices to their needs in innovative ways [32,93], which, in turn, positively affects their well-being [10] and, subsequently, their performance. This rationale is based on social exchange theory [52] and the norm of reciprocity [53], where employees who feel that the organization is investing in them, treating them right, and encouraging them to negotiate their practices will show higher levels of well-being and reciprocate by showing better creative performance.
Therefore, organizations should be open to proposals from their employees about the way they could implement their HR practices, not only to increase the discretionary effort employees put into their work in enhancing their creativity, but also to achieve a greater sense of belonging and a better fit between organizations' and employees' expectations and needs.

The Role of Eudaimonic Well-Being
Eudaimonic well-being showed a significant positive relationship with creative performance, which has two main implications. First, it supports a new reconceptualization of the happy-productive worker thesis [28], as we have considered non-traditional conceptualizations of well-being and performance. In this sense, eudaimonic employees were more creative one year later. Second, it substantively broadens the scope of the model because well-being is now considered as eudaimonic well-being, and performance as creative performance. Eudaimonic well-being is related to self-development, growth, and fulfilment [41], and this type of well-being seems to more strongly enhance creative performance [44]. In fact, eudaimonic well-being was found to mediate the relationship between i-deals and creative performance through employees' engagement in negotiating the shape of these HR practices. Thus, employees increase their eudaimonic well-being, feel more self-realized and fulfilled, and, consequently, display more creative performance.
Although we considered that some HR practices may contribute directly to employees' self-development (e.g., training and development), our results show that these practices only have a one-year lagged effect on eudaimonic well-being through their effect on increasing employees' behaviors to proactively change and negotiate these practices. Thus, in this case, we found a double mediation between HR practices and creative performance through both i-deals and eudaimonic well-being. This double mediation, although not hypothesized, provides interesting information about the distinct individual mechanisms that could exist between the perceptions of HR practices and performance. Eudaimonic well-being, along with the role of i-deals, helps to understand the mechanisms between HR practices and creative performance, as previously requested in recent research [61].

Future Research and Limitations
One limitation of this study is the assessment of i-deals as a single dimension. Even if i-deals, as a concept, can be understood as a one-dimensional construct [90], different types of i-deals can be distinguished, according to the previous literature [32,34,88], which could lead to different results. Future research should investigate whether there are differences when considering different types of i-deals. Nevertheless, our research shows that considering i-deals as a construct plays a significant role in linking HR practices to important organizational outcomes.
Common method variance is another limitation of this study. The use of employer reports about HR practices could reduce common method bias when focusing on employee attitudes [90]. However, we focused on employees' perceptions in order to capture the real experience of these practices by the target of these actions (the employee). Moreover, the use of three lagged waves lowered the possible effects of common method variance [116]. Future research could also introduce the study of the fit between employees and employers-organizations regarding HR practices and i-deal perceptions because it could provide more clues about how these deals are negotiated. Moreover, even though we acknowledged the importance of including other types of well-being and performance variables, rather than the most traditional ones, it was not possible to study differences in the way HR practices affect these outcomes because we did not compare other types of outcomes. It would be interesting for future research to include different well-being or performance outcomes to see if the results are consistent when using different operationalizations of the constructs. However, our study has contributed to broadening the field by considering these less studied dimensions of performance and well-being, which, at the same time, are quite valuable for organizations in times of change and uncertainty.
Similarly, the use of other operationalizations of HR practices more focused on other aspects of the employee, such as work-life balance, could also yield different results because different mechanisms could underlie their negotiation. Future research should incorporate other types of practices to see if they follow the same path as the ones already studied.
Finally, the context might be crucial for i-deals [32]. Thus, future research should take into account potential contextual moderators of the relationship between i-deals and the considered outcomes. Indeed, research has suggested that perceptions of organizational justice and coworkers' beliefs regarding their own likelihood of comparable future opportunity could be influencing the effects of i-deals on outcomes [117,118]. These factors might increase acceptance of co-workers' i-deals and thus facilitate the contribution of those behaviors to the development of eudaimonic well-being and creative performance. The firm's culture may also affect the ease of negotiating HR practices, taking into account whether what employees expect to change is congruent with organizational values and beliefs. Future research should address this issue and study the differences in different organizational contexts, such as the sector, organizational type, or country, where different organizational cultures can be examined.

Conclusions
Our research provides support for a positive relationship between HR practices, eudaimonic well-being and creative performance in the long term. It also contributes to understanding the mechanisms linking HR practices and these employee outcomes by showing the mediator role of i-deals and eudaimonic well-being. In an attempt to identify a sustainable HRM approach, the use of three measurement waves provided us with more information about how HRM might contribute to increasing i-deals, employees' eudaimonic well-being and creative performance in the long term. The three outcomes are considered to be relevant for organizational development and sustainability. Thus, our research showed that the negotiation of HR practices can create a win-win situation for both employers and employees.