Aim: To explore motivational factors for initiating, implementing, and maintaining physical activity following a rehabilitation program for patients with type 2 diabetes mellitus.

Methods: Semi-structured, individual, qualitative interviews with five informants from the InterWalk trial were conducted at three separate occasions; at initiation of the rehabilitation program, at completion of the 12-week program, and 52 weeks after enrolment. Interviews were audio-recorded, transcribed, and analyzed according to Systematic Text Condensation. The framework of Self-Determination Theory was applied to guide analysis after identification of preliminary themes.

Results: Commitment and obligation were emphasized as being motivational in initiating physical activity. Toward the termination of the program, this was challenged by an expressed need for autonomy. Successful behavioral change was characterized by transfer of commitment to a new structure in everyday life, which also honored the request for autonomy. Feeling capable of participating in physical activity was facilitated through knowledge, practical experience, and progress and considered motivational, whereas lack of progress extinguished motivation. Finally, enjoyment of the activity was determining for long-term maintenance of physical activity behavior.

Conclusion: Satisfaction of innate psychological needs leads to more autonomous regulation of behavior and, through this study, we investigated determining factors for extrinsically motivated behavior and factors of importance to the internalization process.