The present paper explores how aging bodies of middle-aged women can enable and constrain participation in physical activity. The study is inspired by the process sociology of Norbert Elias and builds on qualitative empirical material from passive observations (N = 57), focus groups (N = 51), and individual follow-up interviews (N = 21) with middle-aged Danish women who participated in a 3-month research project with exercise intervention. The qualitative study found that awareness of bodily aging enabled the taking up of exercise in the intervention. Additionally, taking up regular exercise in midlife can be understood as a highly rationalized leisure-time activity in relation to societal moral norms of self-responsibility for own physiological health. Furthermore, the qualitative material indicates that participation enabled a self-realization among the middle-aged women, as strong and capable bodies counter to the biomedical view of decline in the aging body.