If you want to be successful as a photographer, you have to know both how to succeed and how to fail, that is, how to embrace not the possibility but rather the inevitability of failure and to turn it into something that promotes learning and growth. This great video examines the idea of just that and how we can grow from failure.
Coming to you from Nigel Danson, this great video follows him as he discusses some of his recent images that he felt were not his best for one reason or another and carefully breaks down what went wrong and how they can be improved in the future. I personally think it's important not to dismiss failures as worthless experiences, as just the act of analyzing where you went wrong can reveal quite a bit about your technique and ideas, which in turn can help you to correct any deficiencies in execution and develop a stronger creative vision for the next time you head out to shoot. I know that personally, I tend to learn a lot more from my mistakes than my successes, and being able to correct them ensures that I won't make the same mistake again when the pressure is on.