Forty-five years ago, at the Mexico City Olympics, a marathon runner from Tanzania finished dead last in the marathon. His name was John Stephen Akhwari.
Akhwari had fallen and hurt his knee. He was bloodied and bandaged by the time he straggled to the finish line, more than an hour after the winner. There, he was asked by the filmmaker Bud Greenspan why he had not quit despite obvious pain.