I hate it when I'm told to JUST be confident or "be myself" if I happen to be in a conversation about getting a girlfriend. Yes, because I can just magically pull confidence out of my ass and I'll be good. I never understood the meaning of "just be yourself", either. And if I somehow tried, I'd probably have a 100% failure rate. Cracked does a good job on this subject; read entries two and three if you're interested.
I can relate to this:
"Reach age 12 or 13 and see a group of females give you the same look they give to a spider they found in the bathtub. Go back and get familiar with that body language that says, "No one will be happy or relaxed until you leave." Go back and live your life in a universe that bites your hand when you try to reach out to it. Then see what your confidence is like at age 23".