I think in my 20s, I intellectually knew every piece of good advice I would send back in time now that I'm in my mid 40s, because I'd read it on lists like these, or in books, movies, etc.<p>The difference is that I could not put it into practice at the time, maybe because I lacked sufficient experience.<p>For example, I've always known <i>in theory</i> that nobody is paying as much attention to what you think is most embarrassing about yourself, because they are too busy being embarrassed about whatever they think they're doing wrong. I knew that, but it didn't matter, I was still self conscious.<p>Now, I've just done so many reps of fucking up in public and seeing the almost total lack of ramifications, or the swift passage of those ramifications from my world, that I actually <i>believe</i> that advice at a core level, it can actually affect my behavior and make me content. I guess it's the difference between knowing and grokking. And, to be sure, I would have been embarrassed to use the word grok in my 20s.