Learning to Handle Failure

Will I fight or flee? This is the big question that cuts to the depth of my character.
My PS I group had our first presentations yesterday and my part was below the standards I have set for myself, dare I say that I thought I sucked. So, do I beat myself up about it for days afterwards or do I learn from it and go on? Yesterday I coundn't even face this question, but it's amazing what a good nights sleep will do.
I know that teachers experience failures, possibly every day, as they work with many different kids in many different situations. Failure can happen in the planning, time management, classroom management, working with colleagues, or in relating to the students. There are many factors that a teacher cannot control. But my concern is not so much about the failures, but about learning how to handle them in a healthy manner. I need to spend less time in self-deprecation and more time in getting on with the next thing that needs to be done. And maybe this skill develops with time and experience.
I am a fighter though and I will eventually have success at handling failure. I know I need to dwell on the positive and be thankful for every opportunity that comes my way.