National Geographic Traveler: California, 5th Edition

Bob Harper is a world-renowned fitness trainer and star of The Biggest Loser USA. He has several bestselling fitness DVDs, his own line of supplements, an online fitness club and the inspirational book Are You Ready! to his credit. He still teaches a local spin class in Los Angeles, where he resides with his dog, Karl.

Greg Crister is a longtime science and medical journalist. The author of the international bestseller Fat Land: How Americans Became the Fattest People in the World, he lives in Pasadena, California.