The long walk

In an ultraconservative America of the not-too-distant future when America has become a police state, the annual marathon is the ultimate sports competition. One hundred boys are selected each year to enter a grueling 450-mile marathon walk. The game is simple: maintain a steady walking pace of four miles per hour without stopping. Three warnings and you're out--permanently. The winner will be awarded whatever he wants for the rest of his life; but a single misstep could be the last.