Why does the narrator describe himself as "not a brave man"?

From the text:

Now, I am not a brave man. I have never learned to drive. I do not fly in planes. I feared women until I was twenty-five. I hate high places; the Empire State is pure terror for me. Eleva- tors make me nervous. Escalators bite. I am picky with food. I ate my first steak only at age twenty-four, subsisting through childhood on hamburgers, ham-and-pickle sandwiches, eggs, and tomato soup.