Books that have become classics - books that have had their day and now get more praise than perusal - always remind me of retired colonels and majors and captains who, having reached the age limit, find themselves retired on half pay.
I think what I would say to my younger self, and probably to younger, just starting-out writers is that a lot of times you're just afraid to put yourself out there, and it's uncomfortable because it's working up the courage to do something, to push yourself to do those things.