Fear

Eleanor Roosevelt once said "You gain strength, courage, and confidence by every experience in which you really stop to look fear in the face. You are able to say to yourself, 'I lived through this horror. I can take the next thing that comes along.'" this is totally true though, you need to realize that everything will be okay and that you have done harder, scarier things or you might have to do those things in the future. Without realizing the fear and pushing through it you will never get anything done and you will be stuck in your shell forever.