People tend to slow down a bit once they got their 40s too. So it isn’t necessarily the injury that is the main reason but it is the main excuse to start letting it slide.
WOW! I turned 50 this year and I'm in better shape than I was back in my thirties. Weights at gym three times a week, trail running around my mountain three times a week, once a week golf(walking) and a daily dog walk. I'm annoyed that Covid has stopped my overseas ski trips, I'm ready to hit the snow again.