Dear Dain,
This is future Dain. You may or may not believe it, but I'm coming to you to impart some wisdoms that you will eventually learn. There is a good chance that you won't listen to me, but here are a few things that you should do.
First, don't waste so much money. Trust me, I have almost nothing that you are going to purchase to this day. The cars were all crap, the junk food just made you fat, and the music all got stolen. Save for school so you can go comfortably.
Next, make peace with your father. We have a good relationship now, but it came about five years too late. Don't worry, he didn't die and he's in good health, but five years wasted is five too many. To be honest, you may not even recognize our relationship considering how things are going for you now. The thing is, you need to mature a lot, stop expecting so much for granted, and give him the respect that is due him.
While on the topic of parents, make sure to tell your mom that you love her more often. The woman would do anything for you. Also, she has really good advice and you will wish that you had followed everything that she advised you on.
Do things on your own terms. Don't rely on anyone but your parents for the necessities of life. Others will leave you hanging at the very worst moments but not so for your parents.
Don't doubt yourself so much. You really can do just about anything that you want. You are just as smart, if not smarter, than the next guy. If you put your mind to it, you are capable of learning it or obtaining it. BELIEVE IN YOURSELF!
Last, stay in shape. It's a lot easier to do it when you are younger than when you are 25. Be disiciplined about it.
Here is a brief five year plan:
18 - Go to school, work hard, keep saving money
19 - Finish your associates and go to University
20 - Go to university, take a few loans if you have to, they won't kill you
21 - Finish up uni
22 - Join the Marine Corps (this is two and a half years earlier than you will anyway, and you'll get out by 27)
Well, that's about it. I'm not going to spoil any of the girl stuff. It had it's ups and downs but you should discover it on your own.
Good luck and have fun!