Primary treatments for prostate cancer (PCa) accelerate aging-related changes in body composition and declines in physical function and quality of life ; the median age at PCa diagnosis is 66 years and approximately 64% of PCa survivors are \> 70 years. The negative side effects of treatments are pronounced in older, sedentary, overweight or obese men with existing comorbidities. The concomitant loss of skeletal muscle mass, increased deposition of adipose tissue and loss of bone mineral density leads to fractures, cancer-related fatigue, frailty, compromised physical functioning, disability and loss of independence as well as anxiety and depression. Regular physical activity reduces morbidity, improves survival and can buffer PCa patients against the negative side-effects of treatment, yet less than 20% are meeting recommended guidelines-and most spend up to 70% of their time each day in sedentary behavior. Targeting a reduction in sedentary behavior by promoting regular spontaneous movement in conjunction with regular resistance training may be an effective approach for PCa patients who are likely to be fatigued and functionally impaired. Traditional theory-based exercise interventions have shown preliminary efficacy for promoting short-term exercise, but can be improved for longer-term efficacy. Traditional exercise interventions are generally not individually tailored, and therefore cannot incorporate behavioral theory to re-engage participants when lapses in self-regulation occur. eHealth technologies can enhance traditional theory-based exercise interventions. The study team hypothesizes that an eHealth delivered intervention can effectively facilitate the development and maintenance of self-regulatory skills that are critical to sustaining long-term behavior change.
