[kreeben]

You sound a bit like me. A trick that helps me overcome these situations is to imagine that the worst thing that could happen, in your case, to fail, has already happened. Then I pause and try to see how this affects me. I imagine people pointing towards me, laughing at me, whispering to each other "he failed", then I start to realize, this is not so bad. A failure is just a failure and other people's feelings towards me in this moment really doesn't matter to me.

This helps me to silence the critics in me and to just get on with it.