Has anybody experienced a gradual lose of confidence as you age?

I've reached my thirties now and when I look back at my younger self I'm always amazed by how confident and lucky I was.

I used to a pay lots of attention to myself: going to the gym, buying nice clothes, using cosmetics, etc. I'm not by any means handsome, but I made up for that with style, confidence and charm, which seemed to worked pretty fine. No matter the circumstances, no woman was out of my league. It lead to lots of rejection, of course, but also to a lot of beautiful stories.

Then, I went into a long relationship which lasted for a few years and now that it has ended, I don't feel the same man I used to be: I'm no longer fit, I have slightly less hair, I'm not that young anymore and I transitioned from smart outfits to jeans and t-shirts.

I'm not sure if this is a middle life crisis or what, but I feel kind of lost and I'm wondering it this has happened to someone else...

Thanks!