As you get older I seem to need more time to recover and there are a lot more injuries.

But the recovery doesn't need to be sitting on the couch. I think at least for me, the best recovery is getting the blood moving again, even if it is light.

and I am still fast at sprints

This is where I have to improve. It has been years. I forced myself about 15 years ago to train sprints, but my feet just couldn't take it. After the surgery, I haven't tried.

the body is just more fragile, I am no longer indestructible.

Now, imagine what it is like for the people who haven't done anything since their twenties or thirties.