"I never thought much of the courage of a lion tamer. Inside the cage he is at least safe from people."-- George Bernard Shaw

George has a point.
I think, when it comes right down to it, our fears--and therefore our need to be courageous--stem from our relationships with people.
In small, look at the bullying some of us faced from bad parents or the mean kids at school.  In large, look at the institutionalized social bullying of women, people of color, and the poor.
From these experiences we observe that our own kind can be pretty terrifying.
People are herd creatures, and when you're booted out of the herd, you lose the safety in numbers that keep the lions from eating you; although the pain of being ostracized is so acute that some might wish to just put their heads in a lions mouth and get it over with.
It takes the courage of  people like Mahatma Gandhi, Martin Luther King, Elizabeth Cady Stanton, and many others (hopefully including ourselves) who address the needs of the "out" group and move them back into our growing, and gradually more tolerant, social mainstream.