I just turned 80. The first time I mentioned a slight tightness in my thighs to a doctor was when I was 67. However, I probably had it before then but attributed it to walking too much. I loved to walk and enjoyed going 4 or 5 miles a day. As the years passed, I noticed I was walking more slowly and couldn't go as far. Most of my walking now is in large stores, with a grocery cart. Once or twice a week, if the weather's okay, I go outside and walk a couple of blocks, using a large, stand-up type walker. This is the irony. The activity I enjoyed most (long walks) is the very activity I can no longer do.