Background The current understanding of the relationship between physical activity involvement and flourishing, as well as the underlying psychological mechanisms, remains limited. Building upon the basic psychological need theory, this study investigates whether and how engaging in physical activities, either as a spectator (e.g., in sports events such as the World Cup) or a participant, explains individual differences in flourishing.

Methods A total of 1201 Hong Kong-based Chinese adults (M_age = 42.90, SD=11.40; 54% female) completed an anonymous online survey from the quarter-final to final stages of the 2022 FIFA World Cup in December 2022.

Results Findings showed that spectator (World Cup) involvement and participant involvement were positively correlated. Moreover, both types of involvements were correlated with flourishing. In addition to the hypothesized positive association with relatedness satisfaction, spectator (World Cup) involvement was also demonstrated significant associations with autonomy and competence satisfaction. Path analysis indicated that associations between physical activities and flourishing were partially mediated by the satisfaction of all three basic psychological needs.

Conclusions This study is the first to apply the basic psychological need theory in the context of physical activity and supports its relevance in understanding individual differences in flourishing. Different stakeholders are encouraged to recognize the benefits of both spectator and participant involvements in physical activities, which may help them develop supportive strategies (e.g., physical activities with parents, sports events for spectators and participants, and funding for media/communities) in mental health promotion.