From Wikipedia:

"Courage, also known as bravery, will, intrepidity, and fortitude, is the ability to confront fear, pain, risk/danger, uncertainty, or intimidation. "Physical courage" is courage in the face of physical pain, hardship, or threat of death, while "moral courage" is the ability to act rightly in the face of popular opposition, shame, scandal, or discouragement."

The power of peer pressure and the desire to conform is immense. Many institutiions squash courage as disruptive.

If we do not praise and teach courage, then we cannot be suprised at its lack.

Edit: I think everyone can increase thier ability to summon courage by practice.