Sad - I hear you 100% because this hits home for me. I played football from age 8 - 26. For the age mathematicians, no I did not play in the NFL, but I did play for a high level semi-pro team for 4 years after college.
Started lifting and training in 7th or 8th grade to become a better football player, and from then end of 8th grade on - my high school had a year round S&C program with an excellent coach who taught us how to lift properly. We were actually very lucky to have him, and he's still at my old HS doing his thing 20+ years later. So that's when I started lifting seriously. Found gear in college because it's football and more of us did it then didn't do it at my school back then. Had plenty of minor to moderate injuries and concussions throughout my football career.
When I quit playing football, I spent about a year just being a gym bro, and realized I hated being a gym bro...became a powerlifter. Fell in love with powerlifting and rode that train until I completely ruptured my adductor when I was 37. Had a million other small - moderate injuries along the way like most powerlifters.
I'm also an Ironworker by trade.
Since I've torn my adductor I went from still feeling close to my peak to going off the cliff Thelma and Louise style. All the little nagging injuries started bothering me around 38. Now I'm 41 and have to be very careful how I train. Sucks getting old. It takes me about an hour everyday from the time I wake up until all the snap, crackle and popping is gone and I can be a normal human for the rest of the day.
I have a few buddies who played short stints in the NFL, and watching them in their 40s is painful. Makes me feel better about myself haha. My business also attends a charity event for Navy Seals every year. Those guys are just completely beat to shit by their 40s. The amount of surgery scars on them is scary. Then you have the other "regular" vets who walked around the dessert or training back at home with 100lb packs on for years on end.
I guess the short answer comes down to "training age" for lack of a better word. If you've rode the injury train, or beat the shit out of your young body one way or the other - it's going to be harder, and you'll just "age" faster. But we all have old man strength. I'm sure could still deadlift 600, or kick the shit out of some young whipper snapper if I had too. I just wouldn't be able to walk for 3 days after. Pick your battles.