I just bought my 19' catboat back in April of last year from an amazing 91-year-old fellow in Florida
last year. He'd been sailing the catboat singlehanded ever since he sold his big boat (a 38-footer IIRC) eight years or so back. Prior to that, he'd singlehanded the big boat from New England
-- mostly offshore
-- every year for a dozen years, doing the snowbird thing.
I'm 66, and Howard is far more agile than I am. When we loaded the catboat on the trailer for me to tow it home, I turned my back on him for a second, and he instantly climbed the five and a half feet or so from the asphalt into the cockpit
with the heavy towing cover in hand and had started putting it on. He moves like a monkey!
His "kids" (in their 70s) had encouraged him to sell the catboat, but when I left he was planning to buy an electrically propelled kayak
for exploring the mangroves. I'm sure most folks can't even envision a 91-year-old getting into or out of a kayak!
Fit old guys like that are my heroes. We might not all be able to keep our bodies functioning well (or at all) to that age, but sailing helps.