Courage relates closely to Ego Strength and Faith, characteristics needed by any writer, as discussed in previous tip posts. Often, just telling yourself that yes, you possess courage, almost magically allows it to emerge.
I believe that the courage to express yourself in your own inimitable way is a prime requisite for the development of an original Voice. Once you find your Voice, your writing becomes more enjoyable and fluent, in my experience. I capitalize "Voice" to distinguish it from the concrete voices of your characters; I am referring to something a bit more ephemeral, i.e. your own personal style of expression.
Let go of the other voices in your head--of critics, parents, other characters in someone else's books, and let your own Voice shine forth. It takes courage and confidence and faith and ego strength to allow that to happen.
I converse on her blog with Uma Krishnaswami, the author of THE GRAND PLAN TO FIX EVERYTHING, about Voice, middle grade, courage, and this crazy writer's life we lead.