Taking longer to heal and recover as we get older isn’t strictly a psychological and/or societal thing. There’s actual evidence (I intentionally didn’t say proof) for this phenomenon. Telomeres (the end caps of chromosomes) shorten with each cell division. The more they shorten, the less they divide and create new cells. Creating new cells and replacing damaged cells is what recovery and increases in physical conditioning really is in a sense.
When cells aren’t being repaired and replaced as easily and/or with “good cells,” recovery and gains are more difficult. This is easiest seen in skin cells. As we age, skin gets looser, wrinkled, etc. Skin cells turn over quicker than any other human cell (I believe). If it wasn’t for the aging process, skin would look and feel just as good as newborn skin cells, as they’re not much older. It’s the quality of the cells themselves - they’re not as good at producing elastin, collagen, etc., and they’re not being made as quickly either. This could very well be due to the telomeres shortening. Environmental factors play an obvious role, but the best environmental factors won’t make up for genetics.
Take the skin stuff I mentioned and apply it to every other cell type; muscle, tendon, ligament, everything.
So yeah, in other words, there’s more to aging than society telling us to slow down and old wives’ tales.
An article on telomeres and research on treatment attempting to lengthen shortened telomeres from Stanford University...
Telomere extension turns back aging clock in cultured human cells, study finds