Self-belief is a form of trust that develops from experience. When you set an intention and commit to doing something, the success or failure of this commitment will impact that trust and either result if consistent, will dominate that self-belief. If you are never sticking to what you say, how can you trust yourself? You track record inspires no confidence because you are never able to fulfill those contracts. The good news is, confidence is something that can be gained by anyone, but it requires building up that track record of trust and maintaining your commitments that you make to yourself.