You never know how much you really believe anything until its truth or falsehood becomes a matter of life and death to you. It is easy to say you believe a rope to be strong and sound as long as you are merely using it to cord a box. But suppose you had to hang by that rope over a precipice. Wouldn't you then first discover how much you really trusted it?
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 have lived through this horror. I can take the next thing that comes along.' You must do the thing you think you cannot do.