Understand what went wrong and what you should have done. Then, move on. Experience is making a mistake and learning from it. Stupid is making the same mistake over and over again. It has been said a thousand times, and it should be said thousand more, the mind is a powerful tool.
Positive thought does honestly create positive reality.
Now, that doesn't mean you just can't sit around daydreaming about what a huge success you are going to be. You have to take action. But, by believing in your ultimate success so completely, you will see solutions that you may never have seen. You will take risks when you might of faltered. It will empower you to succeed.