One of the things I'm trying to address - hopefully before it actually hits me: I've had joint issues as far as I can remember - literally as a kid already, starting w/ my knees. Doctors used to say I grew up too fast. Anyway, the one solution I've found to work, besides supplements like glucosamine, is to strengthen the muscles.
My hands have pretty much been spared so far - especially the left one, and I always assumed that the constant stretching and "exercising" inherent to playing guitar was to thank for that. But I'm not getting younger, and anything I can do to keep those hands in shape...
The other fun part is that I've also suffered from a mild condition called "essential tremors" (I think) since I was a kid. While it's pretty mild - never prevented me from threading a needle or whatever - it bugs me if I have to stretch out of the comfort zone - for example, playing w/ the thumb in the back of the neck, and stretching my wrist and hand.
I have BIG hands, which I think make certain positions - like the "classical" position - even less comfortable. That's what I used to tell my classical guitar teacher when she'd do barre chord and have her entire finger resting against the strings while I only used 2/3 of my index and had to push that wrist way out there and my palm all curved out just to keep the thumb in its place.
Anyway, working out w/ dumbells to strengthen my wrist always seemed to help, and I wish I could do the same for my pinky and the whole outer side of my hand.
So I'm not really counting on that thing to turn me into a fretboard whiz - that's what the studying and practicing is for, addressing the mechanics - but more to strengthen my hands and keep them healthy for as long as I possibly can.