I wrote a piece called How Wrong Should You Be? for Scientific American's Observations blog.
"My best friend in college was a straight-A student, an English major. In part he got all A’s because he is whip smart—his essays were systematically better than everyone else’s. But the other reason was that he refused to enroll in a course unless he was certain he would ace it. Consequently, he never really challenged himself to try something beyond his comfort zone. I, on the other hand, was not a straight-A student. My first semester I took atomic physics with Professor Delroy Baugh, self-proclaimed 'Laser Guy.' I’d never taken a physics course before in my life, and as a reward for my willingness to transcend my comfort zone I received a D."