Quite a few years back I got a call from Laurence, one of my clients.
He informed me that he had just got out of Lake Pontchartrain after his weekly swim. I didn't even know you're allowed to swim in Lake Pontchartrain, but that's another story. He told me that his times had been trending lower, and that he had just swum his best time in years.
We had another client named Marcus who was 72 years old when he had his knee replaced. After that for the next few years he could play nine holes of golf. The next day was too washed out from the heat to play again. He was nearing the end of his golf playing days or so he thought. At age 75 he started strength training. After a year of strength training he could play 18 holes of golf, and the very next day he would play eighteen more holes. The strength training improved his fitness, so did the 27 extra holes golf he regularly played.