Purpose in life and personal growth: The unique and joint contribution of physical activity and basic psychological needs.

This study examined if physical activity (PA) and self-determination theory's basic psychological needs directly or interactively predict older adults' eudaimonic well-being. Participants aged ≥55 years completed five online surveys. At baseline (T 1 ), participants (N = 430) reported on autonomy, competence, and relatedness experienced during PA. PA was assessed prospectively using the Physical Activity Scale for Elderly (recall period = 7 days) for four consecutive weeks (T 2 , T 3 , T 4 , and T 5 ); weekly PA scores were averaged. At T 5 , purpose in life and personal growth were measured using Ryff's scales of psychological well-being. In regression analyses, PA was associated with purpose in life for those reporting low relatedness (b = .04, p = .02). Competence was associated with purpose in life only for those high in relatedness (b = .34, p < .001). Autonomy was positively associated with personal growth for those who also reported high competence. Multiple imputation analyses (N = 430) and sensitivity analyses (n = 304) yielded findings consistent with those from complete cases (n = 182). Encouraging older people to move more may not be sufficient to confer well-being. It may be necessary to help people engage in activities that support their basic psychological needs.