Don’t you just hate it when people let you down? When they’re flaky and don’t do what they say they will do? Don’t let that be your reputation!
Integrity is a key factor in helping you get the self-confidence you need to achieve what you want.
You may not be the best in your field (yet) or the most creative, but if people get to know that when you say you will do something or be somewhere, you honour it. This enhances your reputation. It makes you feel good and the people you work with feel good, because they come to learn that they can trust you: you are dependable and reliable.