It may depend on how you define what "courage" is. Most people believe it is the absence of fear. It's not. It's doing it IN SPITE OF fear. It's acting anyway. Caroline Myss once defined courage as what comes AFTER having done something you were afraid of, not before.
If you want to develop courage, go do what you're afraid of. Start small and build up. The more you practice acting in spite of the fears you have, the most confident - and courageous - you'll feel and be in your life.