Everyone looks about the same (photo evidence to the contrary!), but everyone definitely does not feel the same. Many people talked about having to give up Aikido or other activities because of degeneration and pain in their hips, knees, or feet. However, in my experience, joint degeneration does not necessarily equal pain or loss of function.
One lady in particular comes to mind. She was over 90 at the time, and radiographs showed severe degeneration of her neck. She came to see me one day after sitting bolt upright upon awakening suddenly from a dream. In the process she tweaked her neck. This is a person, who, going strictly by the physical evidence, should not have been able to turn her head more than about 45 degrees. But within a couple of visits, her neck was once again moving a full 90 degrees in both directions.