54. Still use player's frames (Prince Rebel, 95, 350g strung). Only play singles, but almost nothing competitive. Mostly just hit, some volleys, and play some practice points. Biggest emphasis on hitting with good form, good pace, lots of spin, and as much consistency as I can muster. I have a stressful job so I want Zen-ness, enjoyment, and exercise in my tennis, not competitive stress.
Not playing competitively and focusing on form has both helped and hurt my game. I can regularly hit 10-20 well hit balls with good pace in a spin in a rally. I could not do that five years ago. OTOH, I suck in games. I'm a bit of head case and really have to put a lot of energy into the mental part of competitive tennis, but frankly I just don't care. I just want to hit, feel the ball on the strings, and chill out.
I weigh the same as I did in high school, and everything still works. Biggest place I notice the age thing is backing up on overheads, but I don't do that a lot (see above). Obviously a bit slower than 30 years ago, but I still move pretty well.
Eat less now than when I was younger. Even when I play a lot I basically eat the equivalent of one big meal a day.
My only exercise is tennis. I should do some lifting and stretching, but don't. Walk sometimes at lunch at work.
Wine and stout beer drinker, not to excess (usually).