Dean Karnazes is the author of the bestseller Ultramarathon Man, 50/50, RUN!, The Road to Sparta. and A Runner's High. TIME Magazine named him one of the "100 Most Influential People in the World," and he has been featured in Runner's World, People, GQ, The New York Times, USA TODAY, The Washington Post, Forbes, and many others. He's also appeared on The Today Show, 60 Minutes, The Late Show with David Letterman, CNN, ESPN, NPR's Morning Edition, and the BBC. He lives in California.