One of the not-so-lovely things that makes life unfair is failure; specifically, the form that comes when we don't have immediate success in some facet of our lives.
Not being able to accomplish something, especially something that took a chunk of time and energy, is frustrating, to say the least. No matter how much of a downer failure is, you can't let it keep you down for long.
2. Don't Over-analyze: This can make the failure swell to astronomical sizes in your head. Thinking about what could have or should have happened won't help you at all. Even though it seems impossible, try not to dwell on the incident.