I just turned 54. While sometimes I feel old as f@ck, at least I don't look like it.
A decade ago I met Harry Selkow who is an absolute beast. The man looks like he is cut from granite and is 10 years my senior. At that time I was only in the early stages of being less fat.
What I remember most was saying to Harry "I want to get in shape for my age." He yelled at me "F@ck that, just get in shape, no excuses!" Well, I clearly took that to heart.
The point is, for all of you more mature readers like Dylan Thomas said "Do not go gentle into that good night." Keep fighting to be a bad ass. Don't let age be an excuse.
Of course I have aches and pains and it takes me longer to recover. I have to be smarter with my training. But with that said, I can still strive to be better.
In my forties I was stronger, but other than moving big weights, I wasn't good for much else. Now in my fifties I am more well rounded. I am still strong in relative terms and am better conditioned than I have ever been.
The point is, although the metrics may change, you can still set and chase meaningful goals. Don't lament over what you may no longer have. Keep fighting hard for you can.