This week, journalist and author of The Explorers Gene:Why We Seek Big Challenges, New Flavors, and the Blank Spots on the Map,” Alex Hutchinson tackles something athletes and sports enthusiasts think about all the time; how to break through physical barriers. Hutchinson suggests that athletic milestones, and he uses the example of Roger Bannister breaking the 4-minute mile, often have little to do with physical ability and skill, but what holds us back is a lack of belief.