I was in my forties and had been on tamoxifen for 5 yrs and anastrazole for 3 before I started. I am still a very active person, according to Mayo Clinic endocrinologist I talked to at a conference, he said walking was the best. I still clock several miles a day on my own feet. My amazing oncology doctor started them when he felt it was more beneficial than harmful in my case. Full disclosure………….I spend at least part of every day in the barn. Cleaning stalls, exercising and riding horses, etc.