Tim Ferriss is many things. A bestselling author. A kickboxing champion. A horseback archer. The first American in history to hold a Guinness World Record in tango. He has built an enormous following by doing just about everything—and, more importantly, figuring out how to do it all better than most experts and then sharing what he’s learned with the rest of us. He calls himself a human guinea pig. Outside editor Chris Keyes talks to Ferriss about the origins and evolution of his uniquely aggressive approach to experimentation and his self-improvement.