Mine would have to be not going away to college and having a kid too early.
Straight out of HS I went to school at Louisville and became a student manager for the U of Louisville basketball team. There every day learning the game and how to do things from one of the greatest basketball coaches of all time in Rick Pitino. I couldn't handle the work/pressure and left to go back home after a semester. Biggest fukk up of my life. No telling where I'd be at this point if I had stayed
I don't really have any regrets. I've always made pretty good decisions. But I'm only 19 so maybe that will change (I hope not).