Gee OF, sorry to hear of your ailing.
I too am 61, will be 62 in January. I sure get my aches and pains. Just bought a hot tub at the end of summer, built the pad, ran the electrical, still building the deck around it. Hard work, but it has been great to soak in for me and my wife. Even use it in the mornings, eases out the morning stiffness real well.
I believe I know your worry and concerns.....
Ain't all that fun to have to accept the consequences of realizing our lives are ebbing to their collective ending.
Do to circumstance I was forced into a new occupation at 58 years of age. Talk about screwing with my brain......
I was sent to school (training) with kids, crap, talk about a fish out of water!
I didn't do schooling very well the first time around (decades ago) and I struggled to learn all the new computer based technologies associated with much of the advanced job market trades.
I was last out of my class

But in the pursuing years of being on the job, I have surpassed all of them, for there will never be any "program or matrix" that can account for years of living your life by experiencing it.
Oldfeller, this obstacle in my life appeared very daunting at the time, but I can say for having experienced it, I am a much better person on so many fronts now.
You ain't an old horse to pasture now, no, look around you, you got a potpourri of opportunities around you.
Your mind is sharp and never tires of exercise and expanding, don't quit on it.....
Good luck and good hunting old man!