Sit in front of the mirror and repeat this phrase 100 times a day:

"I'm good enough, I'm smart enough and dog gone it, people like me!"

Only after the 100th day of repeating this 100 times a day will you be cured.

Good luck!

~Eric

EDIT: Seriously, there is no magic cure or magic "pill" or magic advice that will give you confidence. Trust me, I know. Ask how I know? Go on, ask, I dare you.