Started Zytiga and Eligard in early January and was worried about the same thing. PSA now undetectable and Testosterone down to zilch. I walk between 6 and 8 miles a day (with my motivation - a young Labrador Retriever) and do resistance training two to three times a week. So far, no problems, in fact, gaining upper body strength due to the resistance training. A healthy diet has led to a 20 pound weight loss and I can honestly say I feel pretty good despite Stage 4 cancer. Radiation starts this month and because my cancer is all within my pelvic area we are going for curative rather than palliative treatment. Stay positive, keep moving, and you'll find ADT to be a relatively minor inconvenience (although hot flashes are a real pain in the butt).