I’m 45.
I would not like to go forward. It’s already started being downhill physically, and I’m happy to take the leisurely route towards senectitude.
Not back to 16. I wasn’t really socialised back then, even if I was at my most physically rigorous.
Not back to 20. Still not properly socialised, and pretty adrift in what I was going to do with myself and who I was.
(I’m still adrift about what I’m going to do when I grow up. Life really is this thing that just happens to you.)
I’d like to go back to 25. When I was starting my PhD, was forming friends for the first time. Before I realised that it was not going to get me a job; before I realised that life just happens to you; before I was compromised and jaded. Back when everything seemed to be opening up for me.