I've never been afraid of public speaking (though sometimes I have been afraid of what I need to say) because I know one indispensable thing -- when anyone rises to speak or perform before a group an immense wave of positive anticipation radiates from the listeners. We want things to go well. We want to be delighted. We want the experience to be entirely positive. I believe that this is the source of heckling -- a strong sense of having one's hopes dashed, of being disappointed.
Worship is a shared experience and not a performance. It is to be judged on its authenticity, its effectiveness, its impact but never on whether or not it was perfectly done. Like life itself, much of its beauty is in its flaws and surprises and serendipity and in the eye and heart and mind of the beholder. There are no spectators. No one comes out unchanged. Even so, be not afraid.