Hmm, honestly, quite a few things. Not so much because it needs changing, as because I'm one of those people who plays RPGs without missing a single thing that is a 'lost-forever' and such. So I would meticulously fix any little mistakes I could remember, like fucking up a test.
I would probably buy some google when it started, too.
You've got the fewest posts with the biggest longevity bar I've ever seen.
I wouldn't trade my life for anything. That being said, there's the little bits and pieces. Starting hockey earlier, learning piano and/or guitar, sticking with some other things. Little things.