Mostly, a hero knows what the right thing to do is, and does it. No hesitation. And no calling any attention to himself. 
(~Lenore Look, Alvin-Ho: Allergic To Dead Bodies, Funerals, And Other Fatal Circumstances)

Heroes are people who over come evil by doing good at great personal risk. Through self-sacrifice, fortitude and action, whether they succeed or fail, heroes provide a moral and ethical framework--and inspiration--for the rest of us.

Unfortunately, our modern definition of hero has been stretched to include all manner of people. The athlete who just set a new sports record isn't a hero. Nor is the "daring" movie star or event eh adventurer out to be the first solo climber to scale Mt. Everest. They may be brave--but they don't meet the definition of a hero, for whatever they achieve benefits only themselves.

Real heroes are selfless.

(~Oliver North, in the forward to Out of the Depths, by E. Harrell)