an off-topic sidenote from me :
I'm only 26, started playing soccer again after 4 years of basically doing nothing and having done sports all my life up until that point. Been going at it for nearly 3 months now and the next day after practise i always feel like an old man, in need of a walking cane

I hope you have a point and i'll soon regain my old physical condition back, but right now i feel like i've peaked
Just wait a couple of years, when you have a few kids to play with, run after, carry up and down stairs, get in and out of cars, get up for in the middle of the night, ...

.
I'm "only" 29, but I feel like I'm 50 right now