Physical activity (PA) is beneficial for both the physical and psychological health of prostate cancer (PCa) survivors. This study identified and examined motives for PA in a cross-section of PCa survivors, including both men in remission and those receiving treatment in the form of androgen deprivation therapy (ADT). Sixteen PCa survivors from Auckland, New Zealand were individually interviewed. Data were analyzed using an inductive thematic approach. Both groups of men were motivated to engage in PA post-diagnosis to obtain and experience the physical, mental, and cognitive health-related benefits associated with regular PA engagement. Past history of PA was also identified as a motive for current PA for men in remission. These findings provide important insight into how PCa survivors perceive the benefits of PA as a part of their cancer survivorship. Healthcare practitioners, exercise physiologists, and cancer support organizations can use this information to further improve PCa survivors’ quality of life and overall cancer survivorship by better promoting PA to these individuals.