With the development of positive psychology in recent decades across the world, a growing number of studies and researchers have shifted their attention from reducing psychiatric and psychological disorders in clinical patients to increasing the mental health and well-being of common people [1]. Among these studies, one continuously proposed argument was that genetics and personality had key impacts on our levels of subjective wellbeing (SWB) and human happiness ^[2][3][4][5][2,3,4,5]. The important individual characteristics that were associated with SWB and its subscales included the big five factors of extraversion, conscientiousness, and emotional stability ^[6][7][8][6,7,8]. Optimism, as an indicator of personal disposition, is generally conceptualized as an attitude toward or cognitive expectancy of positive outcomes [9]. It is believed that people with greater optimism tend to be more favorably adjusted to difficulties, associated with lower levels of anxiety and depression and better physical or psychological wellbeing. In contrast, less optimistic people always expect negative outcomes to happen and thus are more prone to experiencing anxiety, fearfulness, or depression in life [10] (pp. 402–407). It has also been examined that optimism is reliably correlated with improved physical or psychological health, enhanced effective coping skills, and even a higher quality of life and social relationships ^[11][12][13][11,12,13].

While the evidence from previous research has demonstrated a close relationship between optimism and well-being outcomes, our understanding of their mediating mechanism remains modest so far ^[12][14][12,14]. According to the stress and coping theory of Lazarus and Folkman (1984), which emphasized the importance of coping in the relationship between personality and psychological adjustment, it is reasonable to support the idea that optimism can be correlated with SWB according to a routine of various coping styles, such as self-control strategies, cognitive reappraisal, emotional regulation, and social supports ^[15][16][17][15,16,17]. However, most of the prior research has primarily focused on a particular type of coping without regarding it as a broad type of coping (i.e., positive vs. negative coping) in its analyses, and the conclusions were not consistent with each other ^[15][17][15,17]. Moreover, the majority of current research has only been conducted in W.E.I.R.D. (Western, Educated, Industrial, Rich, and Democratic) countries, particularly in the U.S. [18], which makes it worthwhile to further explore the relationships between optimism, coping, and SWB in some East Asian countries.

2. Optimism and Subjective WellbeingB

Optimism is generally conceptualized as involving positive cognition and favorable attitudes toward the future [19]. Two predominant and congruent theories are commonly employed to elucidate the functions and impacts of optimism on outcomes. The first is Seligman’s [20] explanatory style model, which underscores the ways individuals explain past positive or negative events. Those who attribute positive events to internal and stable causes are considered optimists and are often characterized by their characteristics of persistence and hope and expectations of a better future [21]. The second model is the self-regulatory theory proposed by Carver and Scheier [22]. In this model, optimism involves a series of self-identification and assessment processes, motivating active engagement in daily life. When individuals perceive achievable goals and anticipate favorable results, they are more likely to employ increased effort and effective coping skills, even when facing difficulties or challenges [23]. For the sake of simplicity, this research tudy focuses mainly on the trait-like nature of optimism in influencing its psychological outcome, SWB, in Chinese individuals, while it is worth noting that researchers have acknowledged the potential for optimism to exhibit variations over time ^[21][24][21,24]. As a specific domain of mental health and well-being, SWB represents individual evaluations of personal lives, encompassing cognitive and affective dimensions. It is commonly operationalized through measures such as life satisfaction (LS), representing one’s satisfaction or enjoyment in life; positive affect (PA), indicating the frequency of positive experiences; and negative affect (NA), reflecting the frequency of negative experiences in life ^[2][25][2,25]. While the tripartite structure of SWB is popular among researchers, the use of a single-item measurement for SWB has also been deemed appropriate and effective in certain studies [26]. Additionally, concepts such as quality of life and global or domain-specific life satisfaction (i.e., academic satisfaction) could also be employed as proxies for SWB in research ^{[3][13][14][27]}[3,13,14,27]. Alternative methods for assessing SWB encompass physiological measures, memory and reaction time measures, and experience-sampling methods (ESM), aiming for a more comprehensive understanding of changes in feelings over time [2] (p. 35). Based on a comprehensive review of the findings regarding the impact of trait optimism on SWB, the previous research encompasses a diverse array of contexts and participants [2]. These include clinical patients in medical settings, school students undergoing life transitions, and workers or entrepreneurs in organizational environments ^[11][27][28][11,27,28]. To date, two main interests of research have been conducted. The first type includes cross-sectional studies, revealing that lower optimism is associated with increased emotional distress and psychological disorders during challenging times ^[23][27][23,27]. Conversely, higher optimism correlates with greater life satisfaction and more positive emotions, coupled with reduced negative emotions ^[28][29][30][28,29,30]. The second type involves longitudinal studies, demonstrating that greater optimism not only is linked to fewer depression symptoms but also predicts a higher life satisfaction and quality of life at subsequent time points, even after accounting for the initial level of emotions ^[10][14][31][10,14,31]. Evidently, the second type of research provides more robust evidence supporting the beneficial effects of optimism on mental health and SWB compared to the first type. Overall, it is suggested that optimism, particularly trait optimism, maintains a positive association with SWB and its three components.

3. Optimism, Coping, and  Subjective WellbeingWB

While numerous empirical studies have demonstrated a close association between optimism and SWB in the West, the inner mechanism of this relationship is not fully understood ^[12][32][12,32]. Notably, there is a scarcity of studies conducted specifically with samples of Asian or Chinese populations in this field [16]. Considering the motivational component and goal-oriented behaviors associated with optimism, it is plausible to view actively coping with obstacles as an effective means for optimists to achieve SWB, along with other psychological adjustments ^[11][15][23][11,15,23]. In a meta-analysis focusing on optimism and coping relationships, a lot of evidence supported the association between optimism and different coping strategies, such as engagement vs. disengagement coping or problem-focused vs. emotion-focused coping [33]. In summary, optimism had a positive impact on approach (or positive) coping strategies like planning, behavior engagement, and support-seeking, whereas exhibiting a negative impact on avoidance (or negative) coping strategies, such as emotional suppression, behavior disengagement, and wishful thinking. In line with stress and coping theory, individuals are inclined to experience less stress and more positive feelings when effectively coping with life stressors [34]. Recent research evidence also suggests that SWB can be influenced by different types of adaptive and maladaptive coping strategies ^[16][17][16,17]. Adaptive coping strategies, such as problem-focused coping and assistance pursuit coping, are associated with higher happiness and SWB, whereas maladaptive coping strategies, such as emotion-focused coping and low work control, are linked to a lower quality of life and SWB ^[17][35][17,35]. Consequently, rwesearchers  posit that positive and negative coping strategies may have opposing impacts on SWB. Specifically, positive coping strategies are expected to have favorable influences on SWB. In contrast, negative coping skills are anticipated to have unfavorable impacts on SWB. Generally, individuals with optimism tend to possess self-confidence and expectations conducive to effective problem-solving and the development of a high-quality life over the long term [23]. Consequently, in theory, optimism should be associated with positive coping styles, leading to reduced experiences of stress and elevated levels of SWB. Consistent findings from previous studies indicated that optimism may be related to mental health and SWB according to various coping styles, such as increased social support, fighting spirit, humor, and task-oriented coping, particularly in the face of stressful situations and poor health ^[11][13][23][11,13,23]. However, the recent research has presented inconsistent findings, revealing the weak and insignificant indirect effects of optimism on SWB according to some types of coping strategies, such as primary and secondary self-control, in a sample of Japanese individuals [15] (pp. 41–42). These disparities may be attributed to either the mixed and intricate effects coping has on SWB or the distinctions in the sample characteristics between Eastern and Western populations [15].