I took my youth for granted and have been dealing with the consequences ever since. I've (mostly) followed the advice from doctors regarding my "rickety" knees and "bad" back. a) lose weight. b) strengthen muscle groups. c) stop doing stupid stuff. d) remember I'm not 20 anymore.
a) I've lost a tonne of weight through diet and exercise but it's still an ongoing thing. Only halfway to my eventual target but so far so good. I fell off the diet wagon a year ago and after reviewing recent blood test results with my doc I've climbed back aboard. I'm abstaining from the bad stuff and steadily learning to cook healthier recipes. This is winding up a lifestyle change rather than a temporary thing.
b) I targeted my legs thru cycling and walking. The results are extraordinary. I'm no longer a winter cripple. For years I literally couldn't walk a city block without pain. Now I no longer pop Advil for portages like Tic Tacs. My knees still remind me on occasion when they're not happy but that has become seldom. We have a home gym and use it. It helps to have a fireplace and TV there; I can use the rowing machine or stationary cycle while I watch a YT video. My knees will never be 20 again but at least they no longer feel older than the rest of me.
c) I never overload my knees-legs. Rather than assume I'm strong enough instead I assume I'm not. I still climb stairs, hills, and ladders, but take it easy at all times. And very importantly I'm conscience of my pace and gait. Sounds fussy I know but it all has to do with proper posture, especially on portages. The mantra has changed from No Pain No Gain to No Pain All Gain.
d) I don't recognize the guy in the mirror, but I guess I'm stuck with him. I'm not old, I'm only in my 60's. I'm getting used to letting our kids do stuff for me I wouldn't dream of doing before. Lift this, carry that. I don't try to do everything myself and I guess that's okay. I've always hated asking for help, but by following the advice I feel like I'm doing something for myself and getting results.
Sorry for the blab but I hope it helps.