Be not afraid to challenge yourself. Avoid those negatives that says so much. I can't do it. I don't know. When in reality you're not seeking anything better.
If you never ever try. Then, how can you state you can't? If you have never tried to seek knowledge. Then do it. Then you'll never say you don't know. Encourage yourself.
Let all your insecurities fade into oblivion. As you encourage yourself to be better. Be not afraid.