stage-fright

I feel it's all wrong to be nervous," said Maria. "I feel it's lack of confidence. One ought to go right ahead, never minding.""Some people do," he said, "but they're the duds. They are the ones that win prizes at school, and you never hear of them again. Go on. Be nervous. Be ill. Be sick down the lavatory pan. It's part of your life from now on. You've got to go through with it. Nothing's worth while if you don't fight for it first, if you haven't a pain in your belly beforehand.

Stage fright is very common and could be overcomed through step by step processes, but stuttering is a fright that takes time to conquer.