It seems to me, everything always changes, and it would be so easy to say, "That's it, no more good times". But if nothing else, a person has always got their inner-life, and that's a hell of a powerful thing. Does that sound lame, or a cop-out?
I've got nothing in the order of your problems, @LisaB. But debilitating conditions I know a bit about. My insides are scarred up with adhesions, and my knees are F'd; I used to love going for daily runs (5 minute mile plus; there were days I felt like I could outrun a nucular blast if ness). That's gone out the window. Everyone I know is getting older. Two of my mates have cancer. It's grim. There's no two ways about it. But I feel like I know the world and myself better now. It's hard to explain.
@LisaB, you sound articulate and thoughtful, mate. Keep that strength.