What makes a hero a hero?

I was thinking about this Monday night as we drove home from Port Dover. Now, let's imagine that I was in the position to stop a gunman from shooting the queen. Now let us imagine that I did stop him, and I saved the queen from either death or a very traumatic experience. Does this make me a hero? I would say no. Just because I happened to be in the right place at the right time, does not necessarily mean that I am a hero. A hero is one who sacrifices of his time, resources, and even his own life, to fight for a worthy cause (a worthy cause being crime-fighting, spreading of the Gospel, etc.). Do you agree? Disagree? Tell me, if you wish.