Geoffrey Mutai
Credit: Emmanuel Dunand / AFP / Getty Images

Geoffrey Mutai may have won the 2011 and 2013 New York City marathons – and Boston in 2011 – but the Kenyan runner hasn't forgotten his roots. Mutai still competes in local races, including 5-K's and half marathons, in and around where he grew up in the East African highlands. Because a disproportionate number of the world's great runners hail from Kenya, this puts him in competition with both serious runners and excellent amateurs. It also incentivizes the champion, who doesn't have a coach, to keep working hard.