Promoting Subjective Well-Being and a Sustainable Lifestyle in Children and Youth by Strengthening Their Personal Psychological Resources

: Recent research confirms that climate change is having serious negative effects on children’s and adolescents’ mental health. Being aware of global warming, its dramatic consequences for individual and collective goals, and the urgent need for action to prevent further warming seems to be so overwhelming for young people that it may lead to paralyzing emotions like (future) anxiety, worries, shame, guilt, and reduced well-being overall. Many children and adolescents feel hopeless in view of the challenges posed by the transformations towards a sustainable future. Feeling powerless widens the gap between knowledge and action which in turn may exacerbate feelings of hopelessness. One of the tasks for parents, educators, and policymakers is therefore to empower young people to act against global warming, both individually and collectively. Psychological resources were identified as precursors of pro-environmental behavior. A theoretical model (and accompanying empirical research) is presented which elaborates on the links between self-efficacy, self-acceptance, mindfulness, capacity for pleasure, construction of meaning, and solidarity on the one hand, and subjective well-being and sustainable behavior on the other hand. This literature review suggests starting points for programs that aim to promote both psychological resources


Introduction 1.Youth and Climate Change
Global warming and related changes will affect the younger generation more than anyone else living right now [1].For example, they will face more extreme weather events like heat waves and floods when compared with older generations [1].Because of their physical vulnerability, youth will also experience more extreme effects on their health (including birth complications) and deaths due to disasters hitting their physical environment, especially in the global South [2].This circumstance has fueled worldwide social movements like "Fridays for Future" and has inspired courts to recognize the rights of future generations, e.g., [3].Today's young people must come to terms with living a more restricted life and producing a smaller ecological footprint.
Adolescents' awareness of environmental issues has been on the rise [4], possibly because they have often been confronted with news about the effects of global warming from a very early age-sometimes with the understanding of only the emotional message of "threat" and less about its causes.And oftentimes, it exceeds the awareness of older generations: In a survey of a representative sample of 4103 adults, aged 18 and older, living in all 50 U.S. states, 51% of the 18-to-34-year-olds but only 29% of the over-55-year-olds believed that global warming will pose a serious threat in their lifetime [5], possibly because it may take 10 to 15 years before global warming will accelerate beyond human control [1].Data from three nationally representative surveys conducted in the UK in 2020, 2021, and Sustainability 2024, 16, 134 2 of 16 2022 showed an overall pattern of higher levels of climate-related beliefs, risk perceptions, and emotions among younger generations (born after 1996) when compared to older generations, with the gap being larger and more consistent for climate-related emotions than for climate-related beliefs [6].More than 50% of a sample of 10,000 young people worldwide reported that they felt each of several negative emotions (i.e., sad, helpless, anxious, afraid, angry, guilty, and powerless) about climate change [7].Because anxiety is a natural and healthy response to threat, it is not surprising that with increasing awareness young people's subjective well-being has deteriorated [2].
Evidence has indicated time and again that environmental degradation is associated with anxiety and stress as well as with depressive moods, phobias, sleep disorders, attachment disorders, and substance abuse in young people all over the world (for reviews, see [8][9][10])."Climate distress" is experienced by growing proportions of children, adolescents, and young adults [11,12].In sum, perceptions of global warming and its consequences are likely to cause adaptive levels of anxiety stress in many and maladaptive ones (i.e., mental health problems) in a sizeable number of young people [2,[13][14][15].Experiencing floods, droughts and other turbulences connected with global warming may impair their families' functioning in a way that increases their risk for later mental illness [16].Promoting young people's subjective well-being and reducing mental illness by empowering them to collectively mitigate further rises in temperature and to adapt to already occurring consequences through more ecologically sustainable lifestyles seems obvious, especially in light of the fact that "Good Health and Well-being" and "Climate Action" are two of the Sustainable Developmental Goals set by the United Nations for 2030 [17].

Adopting a Sustainable Lifestyle
An ecologically sustainable lifestyle of society describes a long-term considerate use of the earth's finite natural resources [18].For individuals, Hunecke [19] stresses that a sustainable lifestyle not only encompasses ecologically sustainable, i.e., pro-environmental, behavior (PEB).It also includes relatively stable patterns of pro-environmental values, attitudes, and beliefs that are guided by the principles of sustainable development.Many examples demonstrate that individual commitment can provide important impulses that can-when they add up-achieve a long-term impact in the political, social, and cultural transformations ahead [20][21][22].The Fridays for Future movement is the best example of this ripple effect because it started with a single person and has reached global impact within months, e.g., [23,24].Single influencers promoting a sustainable lifestyle on social media channels-so-called greenfluencers or eco-influencers-tend to reach millions of young people and can likewise help them adopt or maintain a sustainable lifestyle [25,26].However, even if young people's attitudes, beliefs, and values are changing towards sustainable lifestyles, for the planet it ultimately comes down to their PEB.

Acting Pro-Environmentally
A recent meta-analysis of 41 independent adult research samples showed that many studies have examined the ways in which people translate their concerns into PEB [27].The most commonly used theoretical frameworks to predict and explain PEB are the Theory of Planned Behavior [28], the Norm Activation Theory [29], and the Value-belief-norm Theory [30] which include values, norms, attitudes, and perceived behavioral control as predictors for PEB and intentions to perform PEB.In a meta-analysis across 56 adult datasets, the Comprehensive Action Determination Model of the determinants of individual environmentally relevant behavior was developed, which combined these most common theories of environmental psychology.It showed that intentions for PEB, together with perceptions of behavioral control, accounted for up to 55% of the variance in self-reported PEB [31].Thiermann and Sheate's [32] two-pathway model of PEB elaborates upon the Comprehensive Action Determination Model, which does not include psychological resources.Thiermann and Sheate [32] emphasize relational variables: Connectedness with nature tends to increase self-transcendence values and to decrease self-enhancement values.Connectedness with nature was shown to influence individuals' personal norms, which in turn predicted their pro-environmental intentions.In their model, empathy (with nature) is predicted by connectedness with nature, by the awareness of the consequences (original model), and by the social context (new variable).Empathy is linked with negative and positive emotions and is expected to be a strong predictor of compassion.In Thiermann and Sheate's [32] theoretical model, compassion influences pro-environmental behavioral intentions directly and indirectly via personal norms.The authors hypothesize that with increased activation of relational pathways, the motivation to act pro-environmentally becomes more intrinsic because the normative pathways are supplemented by an emotional base.
Only very few studies have studied children's and adolescents' pro-environmental intentions or behaviors with reference to aspects of the above-mentioned theoretical models, e.g., [33,34].For example, de Leeuw et al. [33] establish that attitudes towards PEB, injunctive norms regarding PEB, descriptive norms for PEB, and perceived control over PEB accounted for 68% of the variance in high school students' behavioral intentions and 27% of the variance in their self-reported PEB.In this sample of youth, the proportion of explained variance was strikingly lower than in adult samples [31].Although children's and adolescents' possibilities to show PEB are more limited than adults' (e.g., because of limited financial resources or freedom of choice), it is still useful to investigate these predictors because their influence on their PEB through educational measures tended to be high [35,36].However, education for sustainable development which is restricted to the transfer of knowledge may not be sufficient.This was the result of a study in which knowledge of the causes and effects of climate change was not a direct predictor of PEB among youth, whereas social norms and self-efficacy were strong predictors [37].Similarly, in the study by Tamar et al. [38] with N = 284, Indonesian college students' environmental knowledge was not a significant predictor of their general PEB and in the study by Razali et al. [39], the effect of pro-environmental attitudes and self-efficacy on the self-reported PEB of N = 500 14-to 18-year-olds in Indonesia was stronger than the effect of environmental knowledge.

Psychological Barriers to a Sustainable Lifestyle in Young People
Gaps exist between youths' concerns, beliefs, awareness, and norms on the one hand and their pro-environmental intentions on the other hand [40], much like in adults [41].This means that although people have the attitudes, beliefs, and values that correspond to a sustainable lifestyle, they do not (always) act accordingly.For example: The intention to make pro-environmental consumption decisions and the willingness to forego amenities for the environment was low in a sample of more than 4000 respondents between 15 and 29 years from 19 European countries, although the threat of environmental degradation was perceived to be high [42].Correlations between pro-environmental intentions and self-reported PEB ranged between medium sized (r = 0.38) and high (r = 0.59) in samples of 12-to 16-year-olds [33] and 12-to 17-year-olds [43], respectively.These results suggest that additional factors need to be taken into account when predicting PEB, especially when considering that self-reported PEB could be biased by shared method variance or social desirability [44].
Feeling overwhelmed and paralyzed by the severity of the global environmental problems and the magnitude of the necessary transformations are two reasons that may explain the gaps between young peoples' awareness, their intentions, and their behavior.For example, 12% of a representative sample of 14-to 22-year-olds in Germany stated that they did not want to join Fridays for Future, because they felt that "they could not change anything anyway" [45].Indeed, perceived self-efficacy is included in the Theory of Planned Behavior-based models as the locus of control, e.g., [33].In general, "motivational outcomes of self-efficacy are choice of activities, effort, persistence, and achievement" [46] (p.4).It is considered to be an important psychological factor that is also responsible for a person's pro-environmental intentions and actual PEB [47].In Kollmuss and Agyeman's [41] model, a lack of self-efficacy is one of the emotional blocks that acts as a barrier to PEB.Several interview studies concur that individual and collective self-efficacy seems to be low in many young people, e.g., [48][49][50].Lack of self-efficacy seems to affect not only individual PEB but also political activism.This is unfortunate because it is precisely the involvement in protest movements that can empower young people and enhance their personal growth [24,51].Feelings of frustration and powerlessness because of sluggish government activity tend to exacerbate young people's climate distress.This can lead to further impairments in subjective well-being [7], also among the activists [52].However, a higher locus of control or self-efficacy can lead to a greater willingness to act.Depending on the perceived opportunities and control over the implementation of the measures, the willingness to act pro-environmentally was generally positively related to the perceived usefulness of pro-environmental actions among Chinese youth [53].

Further Psychological Resources, a Sustainable Lifestyle with PEB, and Subjective Well-Being
There are additional personal psychological resources besides high self-efficacy that contribute to the promotion of a sustainable lifestyle.Based on the foundations of positive psychology, Hunecke [19] developed a theoretical model on the presumed connections between six psychological resources and a sustainable lifestyle.Noteworthy is Hunecke's [19] idea of regeneration, i.e., that the future state (after a successful transformation) needs to be a psychologically desirable state that people strive to achieve.Hunecke [19] places less emphasis on the actual state or on a dystopian future to be avoided.Psychological resources are supposed to influence not only a sustainable lifestyle but also subjective well-being in a positive way.Thus, Hunecke's [19] model could provide valuable starting points for developing interventions and educational programs to promote both subjective well-being and a sustainable lifestyle in youth.
Unfortunately, it is one of the caveats of positive psychology and sustainability research that valuable theoretical work is seldom accompanied by empirical proof of its assumptions.Although children and adolescents will be affected the most by the consequences of global warming [54], research on the association between their subjective well-being, psychological resources, and sustainable lifestyle is sparse.The aim of this review is therefore to synthesize the literature on how subjective well-being and a sustainable lifestyle are linked with the personal psychological resources of young people, both theoretically and empirically, and to sketch some interventions that promote both subjective well-being and pro-environmental values, intentions, and behavior.Although the theoretical model described below was developed for adults, and although it is obvious that children and adolescents have fewer (and perhaps different) opportunities to act pro-environmentally, the general associations between psychological resources, subjective well-being, and sustainable lifestyles are believed to be the same.

A Model of Psychological Resources and a Sustainable Lifestyle
In Hobfoll's [55,56] Conservation of Resources theory "resources are those entities that either are centrally valued in their own right [. ..] or act as a means to obtain centrally valued ends [. ..]" [55] (p.307).Personal characteristics, such as high self-esteem, are one of the four basic categories of resources people value and try to obtain in order to avoid the experience of stress [55,56].Environmental psychology has elaborated on concepts from Positive Psychology and has identified psychological resources and positive emotions as important precursors of individual PEB [57].Wamsler and Restoy [58] argue that "sustainability is fundamentally about our relationships, i.e., the relationship to oneself, what we believe and value, and how we view ourselves in relation to the world around us" (p.3).These authors emphasize that emotional intelligence is key to the transformation to sustainability and that sustainable behavior goes beyond the individual.Ronen and Kerret [59] propose a common holistic definition of well-being, i.e., sustainable well-being, which encompasses the key components of both Positive Psychology and sustainability and recognizes the links between the well-being of individuals and the well-being of systems like the natural environment.Building on these connections, Hunecke [19,60] has developed the Pleasure-Goal Regulation-Meaning Theory of Well-being, which will be presented in the following.

Pleasure-Goal Regulation-Meaning Theory of Well-Being by Hunecke [19]
Hunecke [19] argues that beyond technological innovations and an increase in organizational efficiency, cultural transformation is indispensable for the transition towards a sustainable lifestyle.Drawing on social-ecological research, environmental psychology, and Positive Psychology, he states that people need to evaluate their future life in a more sustainable society as enjoyable before they manage to change their behavior and maintain these changes over long periods of time.According to Hunecke's [19] theory, well-being can be achieved by three orientations to happiness: hedonism, goal regulation, and meaning.A fulfilled life is based on these three pillars and their associated emotions, such as sensual pleasure, satisfaction, and pride, as well as security, connectedness, and trust.Hunecke [19] identified six psychological resources that support individuals in realizing these strategies for leading a happy life while enhancing both subjective well-being and sustainable behavior.They are divided into foundational resources (self-acceptance, selfefficacy), transformational resources (capacity for pleasure, mindfulness), and directional resources (construction of meaning, solidarity).Their multiple interrelations are displayed in Figure 1.
around us" (p.3).These authors emphasize that emotional intelligence is key to the transformation to sustainability and that sustainable behavior goes beyond the individual.Ronen and Kerret [59] propose a common holistic definition of well-being, i.e., sustainable well-being, which encompasses the key components of both Positive Psychology and sustainability and recognizes the links between the well-being of individuals and the wellbeing of systems like the natural environment.Building on these connections, Hunecke [19,60] has developed the Pleasure-Goal Regulation-Meaning Theory of Well-being, which will be presented in the following.

Pleasure-Goal Regulation-Meaning Theory of Well-Being by Hunecke [19]
Hunecke [19] argues that beyond technological innovations and an increase in organizational efficiency, cultural transformation is indispensable for the transition towards a sustainable lifestyle.Drawing on social-ecological research, environmental psychology, and Positive Psychology, he states that people need to evaluate their future life in a more sustainable society as enjoyable before they manage to change their behavior and maintain these changes over long periods of time.According to Hunecke's [19] theory, well-being can be achieved by three orientations to happiness: hedonism, goal regulation, and meaning.A fulfilled life is based on these three pillars and their associated emotions, such as sensual pleasure, satisfaction, and pride, as well as security, connectedness, and trust.Hunecke [19] identified six psychological resources that support individuals in realizing these strategies for leading a happy life while enhancing both subjective wellbeing and sustainable behavior.They are divided into foundational resources (selfacceptance, self-efficacy), transformational resources (capacity for pleasure, mindfulness), and directional resources (construction of meaning, solidarity).Their multiple interrelations are displayed in Figure 1.According to Hunecke's [19] theory, the personality-strengthening foundational resources of self-acceptance and self-efficacy do not automatically promote sustainable behavior because they are primarily concerned with achieving individual goals and needs, According to Hunecke's [19] theory, the personality-strengthening foundational resources of self-acceptance and self-efficacy do not automatically promote sustainable behavior because they are primarily concerned with achieving individual goals and needs, which can be very materialistic and thus ecologically unsustainable.The capacity for pleasure and mindfulness have a transformative function and "exhibit the greatest potential when it comes to questioning and changing the current lifestyle in a reflexive manner, independently of critical life events and developmental tasks" [60] (p.41).Directional resources are key when it comes to translating intentions for sustainable behavior into action.Both the construction of meaning and solidarity within a group can stimulate reflective thinking, which probes old values and attitudes.New values emerge within the group and are maintained by consensus.Hunecke [19] stresses that these psychological resources are mutually reinforcing and that the omission of one resource may be compensated by another one.

Empirical Associations between the Psychological Resources and PEB
Unfortunately, the associations between psychological resources and a sustainable lifestyle which Hunecke [19] proposed lack empirical support, especially for children and adolescents, because most studies have focused on the negative effects of climate change on people's well-being and the normative, social, and emotional barriers to a sustainable lifestyle.Apart from self-efficacy, few studies exist for adults (and even fewer for youth) that examine the relations between psychological resources and sustainable attitudes, values, beliefs, and behaviors.Nonetheless, some studies indicate at least indirect links or have examined related constructs in youth.The following sections present research findings that support the above-mentioned model, beginning with the relationship between subjective well-being and sustainable lifestyles.They are followed by each psychological resource included in Hunecke's [19] model that is related to pro-environmental values, beliefs, intentions, or behaviors with special emphasis on children and adolescents wherever possible.

Well-Being and PEB
According to Hunecke's [19] Pleasure-Goal Regulation-Meaning model, subjective well-being and accompanying positive emotions are the basis for a sustainable lifestyle and therefore for PEB.In a recent meta-analysis of 78 studies, a moderate correlation of r = 0.24 between subjective well-being and overall PEB was reported for adults [61].Another metaanalysis concluded that nature connectedness was significantly associated with vitality (r = 0.24), positive affect (r = 0.22), and life satisfaction (r = 0.17) [62].The few (quasi-) experimental studies included in the meta-analysis by Zawadzki et al. [61] suggested "that there is potential for creating a positive self-reinforcing cycle between pro-environmental engagement and subjective well-being, which may promote long-term environmental behaviors and enhanced subjective well-being" [61] (p.11).Already experiencing oneself as pro-environmental, i.e., having a green self-image, was already associated with more life satisfaction in a large study with participants from 35 countries, 17 of which were not from WEIRD (Western, educated, industrialized, rich, and democratic; [63]) nations [64].For children, positive relations between well-being, life satisfaction or positive emotions, and a sustainable lifestyle (including pro-environmental values and actions) were supported in samples from around the world.For example, a correlation of r = 0.26 between PEB and well-being (here: ratio of positive and negative emotions) was corroborated in a study with over 1900 fifth and sixth graders from Israel [65].Life satisfaction was positively associated with connectedness to nature, beliefs in environmental behavior, and self-reported PEB (r = 0.59, r = 0.45, and r = 0.20, respectively) in a study with N = 120 10-to 19-year-olds from Spain [66].Happiness was associated with connectedness to nature (r = 0.31) and self-reported PEB (r = 0.19) in a study with N = 296 9-to 12-year-olds from Mexico [67].In a Swedish study, adolescents with higher life satisfaction showed more meaning-focused coping with climate change which was associated with PEB [68,69].And in Italy, proenvironmental behavior was associated with personal and social well-being (both r = 0.21) in a sample of N = 1925 adolescents aged 14 to 20 years [70].

Construction of Meaning and PEB
Meaning-focused coping involves reflecting upon the meaning and benefits of a difficult situation.Because it tends to engender positive emotions like trust and hope [71], it can be considered a psychological resource.The just-mentioned empirical results from the studies by Ojala [68,69] support Hunecke [19] in modeling the construction of meaning to be one of the directional psychological resources that may foster both subjective well-being and actions toward a sustainable lifestyle.
More research supports the notion that engaging in meaningful activities is one of the mechanisms that may explain the link between subjective well-being and a sustainable lifestyle.Using an implicit association test, Venhoeven and colleagues [72] found that environmentally friendly actions were implicitly associated with positive emotions.After analyzing self-report questionnaires, they concluded that this relationship "is not merely a matter of social desirability, but rather a matter of meaning: acting sustainably is perceived as a moral choice and thus as a meaningful course of action, which can elicit positive emotions" [72] (p.8).Klement and Terlau [73] concluded that college students who were involved in (extra)curricular activities in favor of sustainable development tended to report higher eudaimonic well-being related to self-discovery and meaning in life than a control group.Another study underlined the prominent role of environmental hope in promoting both PEB and the well-being of high school students.It highlighted the potential of hopebased programs to achieve both outcomes among adolescents [65].Chawla [74] concluded in her literature review that constructive hope was an important resource for children and youth when it comes to coping with an increasingly degraded natural environment.In her review, she also presented empirical evidence to the effect that social trust [75] and social support [76] can give meaning to actions and thereby encourage children and adolescents.This leads to the psychological resource of solidarity.

Solidarity, Empathy, Compassion, and PEB
According to Hunecke [19], solidarity encompasses both personal responsibility for the welfare of other people and collective self-efficacy.Hill and Howell [77] established a link between prosocial spending and happiness, especially for adults with higher levels of self-transcending values, i.e., concern for other people.In another meta-analysis, Curry et al. [78] found acts of kindness and helpfulness to be related to well-being.Studies conducted within the framework of positive youth development (such as the model from the Australian Temperament Project; [79]) and models of global competencies confirmed Hunecke's [19] assumption that solidarity is also one of the directional psychological resources that may lead to more subjective well-being for adolescents.They established that solidarity in a broad sense was related to adolescents' positive development and emotional health [80].That solidarity is important for the transformation toward a sustainable lifestyle in children and adolescents is confirmed by the results of Fielding and Head [43], who studied two samples of 12-to 17-year-olds and 18-to 24-year-olds.These authors concluded that attributing greater responsibility for the protection of the environment to the community was related to stronger pro-environmental intentions and actions.In contrast, attributing greater responsibility to the government for environmental protection was related to more negative environmental intentions and behavior on the part of the participants.Additionally, Jugert et al. [81] established experimentally that collective efficacy bolstered young adults' pro-environmental intentions by increasing their selfefficacy.Joshi and Rahman [82] discovered that perceived consumer effectiveness was one of the key psychological determinants of young consumers' sustainable purchase decisions.In a recent survey on the Fridays for Future movement, young people in Germany reported that friends participating in the movement and identification with others engaging in climate protection were the strongest psychological drivers for their pro-environmental activism [83].
Solidarity in the sense of caring for other people, however, requires a certain amount of empathy and compassion [84].Links between empathy and pro-environmental intentions, environmental values, and attitudes in children have been corroborated by several studies.In an experimental study, young children took either the perspective of a perpetrator or a victim of environmental harm.Results indicated that children in the victim perspective showed more empathy with the environment because they rated the harmful behavior to be more reprehensible than children in the perpetrator perspective [85].Similar moral judgments were obtained in an intervention study with preschoolers who took the perspective of animals who were living in a forest [86].Pearce et al. [87] specified that identifying with animals (as compared to landscapes) increased preadolescents' empathy and resulted in stronger anticipatory guilt over environmental degradation, which in turn stimulated their intentions towards pro-environmental behaviors.Empathic concern (for other people) among adolescents did not have a direct effect on intentions or self-reported PEB, but influenced PEB indirectly via its effects on behavioral, normative, and control beliefs [33].
Empathy towards animals furthermore mediated the positive relation between childhood attachment to a pet and the avoidance of eating meat as adults [88].Intervention studies have demonstrated that children's empathy and prosocial behavior could be increased through mindfulness interventions in schools [89][90][91], which leads to the transformative psychological resource of mindfulness.

Mindfulness and PEB
In recent years mindfulness has gained much attention in (environmental) psychology because connectedness with the natural world is one of the tenets of mindfulness and compassion [92].Ericson et al. [93] present four main reasons for the well-established positive impact of mindfulness practice on physical and mental well-being: (1) to be engaged in the present moment (and not in the past or the future) is positively correlated with happiness; (2) mindfulness increases empathy and compassion, which in turn tend to enhance social relationships; (3) mindfulness stimulates people to recognize their own values (instead of those promoted by society or commercials) and helps them to behave in accordance with them; and (4) with its stress on post-materialistic values, mindfulness can help in reducing the power of materialistic welfare on well-being.In Ericson's model, mindfulness also contributes directly to sustainable behavior because the chances to achieve personal well-being take center stage in peoples' awareness.When empathy and compassion increase through the practice of mindfulness, they support people in connecting with humans (and animals) in other parts of the world who are affected by unsustainable decisions, and with their natural environment and its degradation.Empirical relations between mindfulness and subjective well-being have been confirmed in meta-analyses for youth, e.g., [94].For adults, there is evidence of an indirect connection with PEB by way of a decrease in materialistic values and an increase in subjective well-being [95,96].In a systematic review, Fischer et al. [97] found some empirical support for their theoretical propositions that mindfulness contributes (1) to the disruption of mental and behavioral routines, (2) to a narrowing of the attitude-behavior gap, (3) to an increase in non-materialistic values, (4) to an enhancement of well-being, and (5) to an increase in prosocial behavior.Because of these ideas, mindfulness was included in intervention programs that aimed at promoting PEB, e.g., [98].A mindfulness-based intervention in schools showed a strong effect on precursors of sustainable consumption behavior in 15-year-olds [99].After another four-month school-based training program with 10-to 12-year-olds, the intervention group showed a significant increase in pro-environmental beliefs, whereas the control group did not [100].Even a short-term mindful activities intervention in a nature reserve with nine-and ten-year-olds resulted in an increase in their nature connectedness and their positive affect [101].In an interview study, adult practitioners reported that they were able to enjoy their lives more fully since practicing mindfulness.They also appreciated the natural environment more intensely at the sensory level, which reinforced their emotional connectedness to nature at the level of experience [102].Raising the awareness of sensory experiences or increasing the capacity for pleasure could be another mechanism by which mindfulness impacts the transition toward a sustainable lifestyle, e.g., [103].

Capacity for Pleasure and PEB
Hunecke [19] explains the capacity for pleasure as enjoying sensory experiences.In the literature, physical pleasure is considered to be part of hedonic well-being and may refer, for example, to the pleasure of eating a nice dinner, e.g., [104].Bryant and Veroff [105] defined savoring as "the capacity to attend to, appreciate, and enhance the positive experiences in one's life" (p. 2) and linked it directly to people's well-being.In their diary studies with undergraduates, Oishi et al. [106] confirmed that the experience of physical pleasure was strongly associated with subjective well-being.Beyond the already reported links between subjective well-being and a sustainable lifestyle, the capacity for pleasure was specifically linked to a sustainable lifestyle: Nurse et al. [107] established that young adults' motivation for sensory pleasure was positively associated with their nature-related behavior, such as hiking and visiting national parks, national forests, or wilderness areas.Apathy or lack of environmental concern toward environmental issues as well as anthropocentrism was negatively associated with the self-reported level of motivation for sensory pleasure [107].Similarly, in a study with 8-to 12-year-olds, girls reported to be more strongly connected to nature than boys.This seemed to be a function of their more intensive sensory engagement with nature in visual, auditory, and tactile terms [108].In another study, young adults' pro-environmental purchasing was predicted by their intrinsic motivation to perform pro-environmental actions, i.e., because they enjoyed doing so [109].Finnish college students' enjoyment of the natural environment furthermore predicted their PEB via their intentions [110].Unfortunately, most of these studies do not provide any insights into the direction of effects because they are correlational.However, since the capacity for pleasure is closely related to, if not part of, subjective well-being [111], it is likely that a sustainable lifestyle and the capacity for pleasure are mutually reinforcing (as noted earlier in this article).

Self-Acceptance and PEB
Self-acceptance is often seen as another dimension of well-being, e.g., [112], which is strongly linked to positive emotions as well [113,114].In Hunecke's [19] model, accepting oneself is one of the foundational resources that at first sight may seem counterintuitive to promote a sustainable lifestyle because this is primarily concerned with achieving individual goals and needs.But self-acceptance can also be viewed as a resource in personality development, which can help in overcoming self-enhancement values (for example through consumption) and in developing self-transcendent values.Little research has been conducted on the predictive power of self-acceptance on a sustainable lifestyle.A closely related meta-analysis noted a significant positive association between self-acceptance and nature connectedness (r = 0.17) in four samples with N = 686 adults [115].Participants in a nature-based intervention study reported that experiences of self-acceptance raised their expectations that they would be able to come to terms with future challenges [116].In keeping with this, another intervention study demonstrated that adolescents' expeditions into the wilderness increased both their self-esteem (a construct which also includes aspects of self-acceptance; r > 0.50; e.g., [117]) and their nature connectedness [118].The positive association between students' eco-anxiety and their intention to act pro-environmentally was moderated by the discrepancy between their self-perception and their desire to see themselves [119].Indirect effects were underlined in a study by Queiroz et al. [120].Selfesteem and environmental values were both higher in adolescents from homes that were characterized by parental warmth.Higher levels of self-esteem seem to be associated with giving environmental values greater priority.In an earlier study, a two-week environmental education camp boosted children's self-esteem, increased their curiosity about nature, and fostered their outdoor skills [121].In summary, the research findings support the assumption that self-acceptance functions as a foundation or part of subjective well-being that helps young people develop and maintain a sustainable lifestyle.

Self-Efficacy and PEB
The other foundational psychological resource at the basic level of Hunecke's [19] model is self-efficacy.It is known to be a strong contributor to subjective well-being and positive emotions in adolescents [122].As mentioned earlier, self-efficacy is a psychological resource that is frequently under study when examining individual preconditions for a sustainable lifestyle and for PEB.In Klöckner's [31] meta-analytic model, behavioral control-a construct closely related to self-efficacy-was a direct predictor of PEB.In a more recent meta-analysis, self-efficacy was the factor that was most closely related to behavior adapting to climate change [123].Studies with adolescents indicated that self-efficacy contributed to forecasting their general ecological intentions which in turn predicted their general ecological behavior [124] and their self-reported PEB [33,37,43].In addition, greater self-efficacy was associated with high school students' increased participation in climate activism [125].Hunecke [19] assumes that both self-efficacy and self-acceptance function as resources to become more independent from social comparisons which in turn increases personal sustainability.

Implications for Practice
The results reported so far suggest that promoting subjective well-being by strengthening psychological resources can help children and adolescents adopt sustainable lifestyles, when combined with providing them with knowledge about current and impending climate changes and when teaching appropriate coping strategies.Strengthening psychological resources may indeed be the factor that enhances the success of environmental education.A recent meta-analysis over N = 169 studies with 519 effect sizes established the effectiveness of environmental education for children's and adolescents' environmental knowledge (g = 0.953), attitudes (g = 0.384), intentions (g = 0.256), and PEB (g = 0.410) [36].None of the examined moderators of program effectiveness (i.e., characteristics of the study, the design, the intervention, the participants, and the outcomes) were significant.It thus remained unclear which characteristics of the educational programs were responsible for their success in the various domains.Psychological resources may be the missing link that accounts for the influence between environmental education and a sustainable lifestyle in youth.
This idea suggests new approaches to education for sustainable development at different stages of young people's lives.Education could focus, for example, on strengthening psychological resources rather than just addressing the negative impact of the climate crisis on subjective well-being as a motivation for PEB.Ronen and Kerret [59] proposed a holistic definition of well-being, i.e., sustainable well-being, which encompasses key components of both positive psychology and sustainability and recognizes the links between the well-being of individuals and the well-being of the natural environment.By integrating the benefits of positive education and environmental education into a coherent approach, Ronen and Kerret [59] provided a roadmap to guide schools (and other educational institutions) in their approach to environmental education with the aim of enhancing sustainable well-being.Three of their 10 "thinking rules" were (1) think and feel positive, (2) identify and use individual strengths, and (3) together and integrative.With these rules in mind, caregivers and teachers could teach children from an early age onward to be aware of their personal psychological resources and to strengthen them.Learning to enjoy food through sufficient time for meals and teachers as role models [126] and regular walks in forests and parks with a mindful sensory experience of flora and fauna [127], for example, can be organized in nearly every preschool, kindergarten, or school alongside explaining the basics of ecologically sustainable behavior [128,129].Forest schools provide an opportunity to teach primary and secondary school students not only about the climate crisis and ecologically sustainable behavior but also to instill solidarity and social responsibility in them [130].When in nature, new emphasis could be placed on experiencing pleasure, including the pleasure of learning [131].Sobel [132] provided a comprehensive overview of outdoor (pre)school approaches around the world that have been developed to foster children's connection to nature.When empirical results were available, they consistently emphasized the positive effects on children's well-being and behavior.Thus, approaches to promoting sustainable lifestyles through education for sustainable development already exist in many countries and are well suited to be expanded by another focus-that of promoting psychological resources which are part of the "inner nature" of human development.

Implications for Research
In research, there is an urgent need for quasi-experimental interventions to establish the causal links between strengthening children's and adolescents' personal resources while at the same time preparing them for a sustainable lifestyle, organizing collective action in support of the transformation, and adapting to the unavoidable changes in the environment.Unfortunately, many of the studies cited above used correlational (rather than causal) designs.Most results stemmed from cross-sectional studies which relied almost exclusively on participants' self-reports of their PEB with their well-known flaws.Most importantly, none of the studies have collected data on the link between psychological resources and subjective well-being with a sustainable lifestyle.Only a handful of interventions on the promotion of a sustainable lifestyle among youth meet the high methodological standards for meaningful evaluations, by having, for example, a randomized controlled design.Future studies on the relation between psychological resources and PEB should close this gap by meeting higher methodological standards in longitudinal, randomized controlled trials and quasi-experimental intervention studies.

Conclusions
Today's youth will bear the brunt of the unpleasant changes of the rapid increase in global temperatures (climate adaptation) while their PEB may have little effect on local warming [1].It is therefore necessary to support the younger generation in developing and strengthening their (psychological) resources for the cultural, social, and political transformations that are needed to mitigate climate change and to alleviate the worst consequences-by individual sustainable lifestyles and by collective climate activism.Hunecke's [19] Pleasure-Goal Regulation-Meaning Theory of Well-being provides the theoretical framework for this review of empirical research on the associations between six psychological resources and PEB in children and youth.Empirical research on the promotion of psychological resources to increase both well-being and a sustainable lifestyle in young people was found to be scarce.However, for each of the six psychological resource construction of meaning, solidarity, mindfulness, capacity for pleasure, self-efficacy, and self-acceptance, at least indirect associations with PEB and well-being were established, which advocates for the fostering of children's and adolescents' psychological resources in order to promote their PEB is backed by empirical support.Future research should focus on longitudinal studies and randomized controlled trials that allow conclusions to be drawn about causal relations between the constructs under scrutiny.Nevertheless, the existing literature indicates that empowering youth will not only help them to downregulate their eco-anxiety and increase their well-being and agency but will also narrow the gap between their environmental concerns, attitudes, and intentions and their actual PEB.

Figure 1 .
Figure 1.Interrelations between six psychological resources for a sustainable lifestyle from Hunecke [12,48].Note: From "Psychology of sustainability.From sustainability marketing to social-ecological transformation", by M. Hunecke, 2022, Springer, (p.94).Copyright 2022 by the Author(s), under exclusive license to Springer Nature Switzerland AG.Reprinted with permission.