When I was under sixteen years of age, fear of failure used to hold me back from pursuing my dreams; as well as other people opinions, which had a similar effect on me. I needed some self-confidence, and a lack of such really disabled me during my younger years.
Confidence is a choice, as is believing in yourself. If you are not prepared to believe in yourself, then why would anyone else? How can you expect them to, if you are not your number one fan to begin with?