It depends on whether the strain comes from lack of use, or true debilitating corrosion of the biological parts.
The latter, all ideas here are good.
The former, avoiding aches and pains that come with getting older and back in shape is the worst thing any one who is a "mature" citizen can do.
I had an Aunt I was taking care of, who was in her late eighties, and who was becoming increasingly immobile due to, simple a fact; Her attitude was, I will not do it because I do not want to.
She had a chair, the only one she would sit in, that was labor, for me to get out of when I was in my fifties; Her therapist told me that my continuing to use that chair for her was the best thing I was doing; it was forcing her to use , and maintain, muscles, to stand-up, she would not use any more due to her abandoning of normal house hold chores, by choice. (There was unknown medical psychological reasons causing her change, also, but she was still a stubborn German.)
