It's difficult to believe in yourself because the idea of self is an artificial construction. You are, in fact, part of the glorious oneness of the universe. Everything beautiful in the world is within you. No one really feels self-confident deep down because it's an artificial idea. Really, people aren't that worried about what you're doing or what you're saying, so you can drift around the world relatively anonymously: you must not feel persecuted and examined. Liberate yourself from that idea that people are watching you.