Is there an age where you decide to just 'let it go'?

Not talking suicide. But, I mean more like an age where you know you won't be dating anybody and that you don't care if you let some of your health slide. Get a little chubby, drink some beers that you never did before, smoke like you never did before when you spent years avoiding the stuff when you were younger.

Stuff like that. I think I might get into smoking when I'm more into my 40s or something. I don't care, life would've long pass me by then, it isn't like I'm going to be a successful individual at 55 or something.