My kids and I spent 2 hours today visiting with a couple who have great-grandchildren the age of my kids. The wife can get around, and really enjoyed sitting and talking with the kids, and they with her. She was amazed at how quick their minds were to grasp new ideas, and happily showed them all sorts of things. He is also mobile, but losing his strength and flexibility. He was still sleeping at 1pm. He wanted to do all sorts of things, but he can't use the post-hole digger, can't lift his end of things, can't bend over well, gets up slowly, etc. The mind is willing, but the body is weak. He's still able to bench over 100 pounds, walks 2 miles daily, rides his sport quad, etc, but they're slowing down, selling their stuff, and moving to a place where someone else will care for the building and the grounds.
Their place was a secluded, gated community with a 160-acre lake (with beach), indoor and outdoor swimming pools, their own security, a full administration, gatekeeper/guard, picnic areas, counts for various sports, a golf course, etc. They even have a small convenience store. But they can't get into one of their big trucks, anymore. I moved it for them, since it was in the way.
When I was a kid, I was at a jobsite while a house was being built. My job was to collect stray nails (babysit myself). There was an old man there who never wasted a move, and worked longer and harder than anyone else, but he always moved slowly. Most everyone else was 20 or more years his junior. A 20-something kid showed up wanting a job, but was getting no traction. My dad told the kid the crew was full. The kid said he could replace the old man. The wager was that, if the kid could outdo the old man, the kid was hired; if not, his labor was free. The old man never seemed to take notice, but everyone else sure did, to the point that work slowed down. At the end of the day, the kid's tally was well below that of the old man. The kid knew it well before the day ended, but finished the day. My dad hired the kid for the next job, and told him nobody ever outdid that old man. My dad assigned that kid as the old man's partner. That kid now owns and runs a construction business. The old man died on a job site in his 90s. I wasn't there, but apparently he still put in a good day's work. Originally, his excuse was that he was getting away from his wife, but after she died, he said he had nothing else to do, so he kept working.