Better health??? Since I have started diving, I have put on almost 100 lbs, most all my hair has fallen out, my vision has gone to hell, my hearing is now terrible and I have tinnitus, my low back is a mess, my thoracic spine ain't great and my neck is not good, I have arthritis in my hands, knees and probably elsewhere, I've had cancer cut off my face (most likely from excess sun exposure) and my endurance is nothing compared to what it was when I started diving.
I am not sure but some of the others approach to the indirect benefit of diving seems to have worked for them. I guess its never to late to reevaluate and possibly try something that could help. Just want to leave room for a positive side to what you are experiencing in regards to physical health. As far as metal well being I would guess you you probably agree that it probably provides you with two things:a good mental relaxation session, and can at least keep your mind sharp and alert, possibly encouraging good mental development as we age.