Midlife's challenges, changes, and demands can create barriers to maintaining groups, activities, which, for some, include attending in-person group exercise classes. As a potential solution, on-demand group exercise platforms (e.g., Les Mills+) offer agency over participation, anonymity, and community interaction. This research explores how social identification processes shape participation in Les Mills+. Twenty Les Mills+ participants aged 40-64 were recruited for three data collection stages: (1) an initial semi-structured interview on exercise history and Les Mills+ usage; (2) a two-week post-exercise diary capturing social identification experiences; and (3) a follow-up interview to discuss topics from the first two stages. Results highlight how, through anonymous participation in on-demand group exercise, participants experienced a sense of agency, inclusion, and community while feeling socially supported both during and after participation. Findings from this study suggest four factors that can impact social identification within on-demand exercise platforms, namely (a) creating a collective event to foster unity, (b) providing anonymity and agency to enable increased exercise trial, (c) enabling exercise participation from self-excluded groups, and (d) amplify life-stage similarity and support on-screen and via social media.