Turned 70 last November (diving in Raja Ampat, Indonesia for 28 of 29 offered dives) and this is year 54 of diving.
Just returned from Maldives logging 24 dives some in current and deep-ish profiles to hook in and see sharks plus 35' day and night manta dives.
These days 3 good dives and an occasional night dive is plenty for me. Tropical warm water after decades of diving drysuit, Great Lakes, Pacific Northwest, etc. well before dive computers, too. I did it when young but sure don't miss it now. I like reefs, with or without some wrecks (Red Sea, Pacific, etc. too )
Health is good and I exercise (mostly cardio fast walks) and enough strength work outs to handle a typical 80 cu. ft. tank, 2.5mm or very limited 5mm suit to stay warm. That also means less weight coupled with the simplest lightweight tropical BCD, the discontinued Aqualung ZUMA. Yeah, and one of those integrated Aqualung Airsource which my buddies know to grab my primary and I'll use the Airsource to get us back up safely.
I always dive a couple Suunto ZOOP Novo wrist computers (I have 4 picking them up with practically no dives on them for $150.00 -ish.) A Youtube video showed me how to set it easily and the battery seems to last forever but I can change it myself too.
Paired with a simple SPG with NITROXI get plenty of bottom time but also have no qualms if someone I'm diving with wants to come up at 45 min or over an hour as long as NDL are OK and gas is plentiful.
Last thing I'll say is this........
Your average sport diver has seemed to forget we are SWIMMING underwater.......
With all the crap people strap on I guess I shouldn't be surprised they struggle but many have marginal watermanship......Kind of sad because that's what attracted me to diving way back when......
Stay fit, rest more, take less crap in the water and enjoy the show.
I plan to for 5-10 more years