How do you get brave?

Xander and I had a pretty abstract topic for conversation: bravery.

Xander: "Sometimes its dark out and scary"
Mommy: "I like it when it is dark outside. I'm not scared. I'm brave."
Xander: "I not brave...I am brave sometimes. How do you get brave, mommy?
Mommy: "Well, you have to practice doing scary things over and over. Then, you get brave."
Xander: "Uh-huh. Ok. You have to practice."