This study aims to examine whether Smart After-Care service (Internet-and mobile-based lifestyle intervention) has an effect on patients' satisfaction and clinical outcomes in patients with prostate cancer on androgen deprivation therapy. Patients with prostate cancer on androgen deprivation therapy will participate in the study. The study design is a randomized controlled trial. The patients were randomly assigned to intervention or usual care groups. Intervention patients received Smart After-Care service for 3 months. Primary endpoint was an increase in patients' physical function as assessed using 2 minute walking test. Secondary endpoints included improvement in muscle strength, short physical performance battery, body composition, and health-related quality of life.