Alastair Humphreys is an adventurer, author, and motivational speaker. At the age of 24, he cycled around the world, riding 46,000 miles across five continents and 60 countries. More recently he has walked across southern India, rowed across the Atlantic Ocean, run the Marathon des Sables, completed a crossing of Iceland, and participated in a couple of Arctic expeditions. He was named as one of National Geographic's Adventurers of the Year for 2012. His previous titles include "The Boy Who Biked the World," "Ten Lessons from the Road," and "Thunder and Sunshine." Ranulph Fiennes is an elite soldier, athlete, mountaineer, and renowned explorer, and the author of 19 books of fiction and nonfiction, including "Killer Elite" and" Race to the Pole."