Belief is a powerful tool. If you have self-belief you will be instilled with self-confidence.
Belief really is a double edged sword though because we can definitely have negative beliefs about ourselves, about others, about the world, and about the possibilities that exist for ourselves, others, and the world. Belief, if used positively, can really create optimism and open yourself up to all potential positive possibilities.
An important aspect of belief is that it requires something. For belief and if we're thinking positively, hope, requires us to take action as well. We cannot believe and stand by idle, waiting for our beliefs to 'come true' without having to take any action. If we really do believe we will want to take action to ensure we are working toward making our beliefs and hopes a reality. Belief, then too, is tied to passion and our purpose for living. We must believe in ourselves, our passion, our gifts, our abilities, our knowledge, our experience, our interests, our skills, in order to bring and breathe life into these aspects of ourselves.
Belief can start anywhere. It can start by believing in someone, in some thing but it will always lead back to yourself if you first believe externally.
Believe in you and your purpose and take action toward achieving that which you want in your life.