This chapter presents an autoethnographic analysis of a 12-week CrossFit® (high-intensity functional training) programme in relation to the lived experience of combat-related PTSD. Framed by Self-Determination Theory (SDT), the analysis examines how the psychological needs of autonomy, competence, and relatedness were activated through CrossFit’s peer-supported, mastery-oriented culture. Drawing on reflective journals, field notes, and memory work, three narrative vignettes trace a trajectory from initial scepticism to self-endorsed engagement and sustained participation embedded in community. The analytic commentaries highlight how autonomy was restored through self-directed choice of movements and scaling, competence was reframed from performance metrics to emotion regulation outcomes such as reduced hyperarousal and improved sleep, and relatedness was fostered through shared effort and micro-rituals of support that countered isolation and avoidance. Positioned on a moderate evocative–analytical continuum, the chapter integrates personal narrative with theoretical reflection to generate practice-proximal insights for coaches, clinicians, and veterans. It concludes that SDT-informed CrossFit® can serve as a trauma-responsive adjunct to care, reducing symptom burden and reliance on medication while rebuilding identity, agency, and social connection.