What you state is technically true, but this is life. We all age. I’ve made a lifelong commitment to fitness. I will work out and train in some capacity until I am on my deathbed. The point is you try and look as good as you can at whatever age you are. Look at guys like Sylvester Stallone. He’s pushing 80 now. He still looks damn good. Of course he knows he’s not what he was when he made Rambo or his other Rocky movies. Lol but A dude in his late 70s or whatever he is now? He’s still top of the pack. And if nothing else, the mental edge you keep from training is unlike an edge you’ll get from anything else in life.
We’re all going to get old and fucked up one day, but you might as well play the game and fight it as long as you can.