I like intensity. I like pushing boundaries. I like exerting myself to the limits of exhaustion. And then some. That’s why I was drawn to long-distance running as a kid. I still remember watching Frank Shorter win the marathon in the Olympics in 1972. His lanky body. The gaunt endurance in his face. His steady stride. There was a majesty as he entered the coliseum, the sense of a soldier coming home after a long and punishing voyage. I didn’t know someone could be so exhausted, and I wondered if he’d collapse in that last lap.