It IS depressing when you feel like your body is letting you down and you're no longer able to do the things you enjoy because of various aches and pains and problems. I saw that somebody suggested Yoga and I wanted to add that you might want to check out Pilates,too. I'm not a big fan of Yoga classes but do enjoy Pilates. Both classes are offered at the gym I go to.
I guess we all reach a point where we accept what we can do with the limitations our bodies have, but that doesn't mean we have to give in easily! My husband is a quadraplegic. Don't picture some poor guy stuck home in a wheelchair.....he's out today participating in a bass tournament. He's the only disabled guy in this particular bass club and he gives the other members a run for their money! He has a great attitude and has really taught me that if you want to do something badly enough, you'll find a way. It's not always easy and sometimes he has to accept that there are just certain things he is going to be unable to do. But he stays positive about it all, and I think that's really the important thing.
Accepting our limitations is not an easy thing to do but sometimes I think it leads to a new path......something else we enjoy, or that let's us create or whatever it is we enjoy doing, that we might not have found otherwise.