The one quote I like to think of every day, and I only wish I had heard it sooner.
"Courage is not the absence of fear. Courage is being scared to death and still pushing forward." - Someone whose name I forget.
Also:
-Think of the 5 people you look up to the most in your life. Are you at all like them? No, if you were you would be looking straight at them, fix that.
-Never tell yourself you can't do something. You're just looking at the wrong angle. (Ah, inside jokes only I will get...)
-Anyone can "know" something, what sets you apart is the initiative and effort put into it. If you ever find yourself saying "I know enough to pass the test", then you don't know it.
-If you look at someone and say "I need to get the hell away from him/her before they find out about...", then walk up and tell them what it is you screwed up on. If you do this immediately, you can usually find a way to fix it.
-Communication is never detrimental, though it is scary as hell. Talking the person you least want to somehow always works itself out.
-You can't memorize everything. Stop trying to, and learn the concept, the details will work themselves out.
On a more personal note:
-When she's been dating the guy for 5 years already, just move on. "Being friends" is not good enough.
-Don't break up with the girl who is your only partner when trying to make the coolest video game you ever could. It will not end well. (Admittedly, better than I thought it would)
-Measure angles from the normal, not the tangent. It will save you about 6 months of your life.
-That time in Spanish when you had 2 days to do the video you were assigned 3 months ago with no group, song, or video camera and you told yourself it would work itself out. It actually did... Never even picked up a camera.
-F = ma is the most useful thing you will ever learn.