Surf therapy is an intervention increasingly being utilized to tackle a range of health inequalities for military veterans. While increasing evidence demonstrates the effectiveness of surf therapy, there has been limited exploration of program theoretical explanations as to how it achieves positive outcomes. Theoretical understanding is important as it allows for service optimization, monitoring and further development. The current study utilized a pragmatic qualitative approach to explore theoretical mediators of the outcomes of Jimmy Miller Memorial Foundation (JMMF) surf therapy intervention. JMMF is a California (USA)-based program supporting military veterans facing mental and physical health challenges. Eighteen people who had participated in JMMF interventions (12 males and 6 females; mean age = 42 years; standard deviation = 11 years; range 28-71) were interviewed in depth about their experiences of the surf therapy intervention. Data were analyzed through constant comparative analysis and memo writing in line with pragmatic grounded theory. Two core intervention categories (relating to service delivery) were identified: “Constant challenge tackled at own pace” and “A non-judgmental familial safe space.” A further three individual categories (relating to participants) were identified: “Accomplishment,” “Respite,” and “Social Connections.” One contextualized category was identified; “Physical Therapeutic Elements.” Furthermore, a culture of “Reframing Failure” pervaded every element of the intervention. The findings demonstrated strong links to self-determination and flow theories which suggest potential theoretical frameworks for better understanding of the constructs that underpin surf therapy. The findings provide empirical evidence as to how best to optimize and expand JMMF service delivery in the US and potentially for surf therapy in wider veteran populations.