The king of ultrarunning:Jim Walmsley is America’s best male ultrarunner. He once ran from rim to rim to rim of the Grand Canyon — 42 miles with 12,000 feet of climbing — in under six hours. Another time he broke the course record at the Western States 100-Mile Endurance Run in back-to-back years. Now, he wants to prove that he can conquer a race as short as the marathon (26.2 miles) by fighting for a spot on the Olympic team.(The New York Times) “A lot of people train to have their best day ever. In ultrarunning, you learn to train for your worst.”