The purpose of this study was to investigate the role of the constituent processes of psychological flexibility (contact with the present moment, acceptance, cognitive defusion, self-as-context, value clarification, and committed action) in supporting physical activity (PA) maintenance. A total of 9 physically active participants were interviewed using the Scanlan collaborative interview method. Participants were asked to discuss their strategies for maintaining PA, before being asked whether the 6 psychological flexibility processes played a role in their PA behavior. Data were analyzed using a combination of deductive and inductive thematic analyses. Acceptance, cognitive defusion, value clarification, and committed action played a role in participants’ experiences of maintaining PA. Contact with the present moment and self-as-context were reported to be relatively unimportant to participants’ PA maintenance. Cultivating acceptance of PA-related discomfort, defusion from unhelpful thoughts, clarifying the value of PA, and encouraging commitment to PA would likely benefit individuals’ efforts to maintain PA.