One way to develop faith and confidence is simply to practice using it. If I were to ask you whether you're confident that you can tie your own shoes, I'm sure you could tell me with perfect confidence that you can. Why? Only because you've done it thousands of times! So practice confidence by using it consistently, and you'll be amazed at the dividends it reaps in every area of your life.
Awaken the Giant Within (ed. Simon and Schuster, 2007) - ISBN: 9780743274333