re: If you could go back in time, what advice would you give to the 18 year old you?

1) The girl you're with now is NOT the girl you're gonna marry, so end that today. You're gonna waste 6 years and all of college with her, only to find the right girl afterwards. You're going to go through a ton of heartache and lose tons of money for nothing. Have fun between now and then. As far as that goes, track the right one down even sooner because you'll know it when you meet her.

2) You're in school for a fricking reason. Learn things. Also, you're not gonna go to law school so your stupid Political Science degree is going to be utterly fricking worthless. Change Majors TODAY to something useful.

3) Force your Dad to stop smoking RIGHT NOW! If you wait, he eventually will but only after he ends up with Emphysema and will die right before you have your first son. He stops now you can probably prevent that. In fact, take me to him I'll tell that a-hole myself...

4) Get in great shape now. It's so much easier to stay in shape than to get in shape at 45 or later.

FWIW, this is what it's like having sons. My oldest listens, but my youngest (16) is my mirror image and it's like talking to a wall. At points I'll actually tell him, "Hey man...you realize I'm not talking to you as your Dad, but basically as you from the future, right? I'm begging you to listen."