I am 34. I probably always overtrained with weights and another sport combined at least for the last 10 years. At 34 i feel really good just backing off the training a little from what i do, i just train every 2nd day now. I also don't eat as much because i realised i didn't need to eat 5-6 times a day so i feel better with less food in me.
Training wise, i hit a high peak powerlifting at 21 and even leading up to that at 19-21 i was really feeling those lifts. Now i do very few sets and just go to failure and look better than ever. I don't try and lift as heavy, i was doing that until about 2 years ago then just went fuck it i'll just pick a weight and do it slowly and go to failure.
I had worse injurys when i was younger, i fucked my elbows at 17 doing heavy tricep movements, but now with the lighter training and pumping it out, i have no injuries or any joint pain at all. Once you build the muscle, it stays, you don't have to keep lifting heavy. Same with eating. I just go along i stay as lean as fuck now and feel much better. I sleep less and work harder and feel better.
Obviously age changes things, for me it made me realise lately i don't need to train so much, i actually look better training less as the intensity is still there and i know what to do after all these years without doing too much. The skin is thinner and the definition is far better than when i was younger with thicker skin. I would probably peak physique wise at 50? In terms of face aging no drinking or smoking etc, i don't age much at all. Not compared to others my age who live harder.