Mark Sisson is widely regarded as one of the forefathers of the ancestral health movement. A former world-class athlete in the marathon and Ironman Triathlon, he presides over a wide-ranging Primal enterprise, featuring the Primal Kitchen line of healthy condiments, The Primal Health Coach Institute, a line of premium performance and nutritional supplements, and numerous books and online educational courses. He publishes daily tips and inspiration at MarksDailyApple.com, the top-ranked blog in its category for the past fifteen years. Mark lives in Miami Beach, Florida with his wife, Carrie, where he standup paddles the inland waterways, plays Ultimate Frisbee against hotshots half his age, and enjoys his new role as a grandfather.

Brad Kearns is Mark Sisson's longtime co-author, host of the B.rad Podcast, and an elite masters athlete. He broke the Guinness World Record in Speedgolf at age 53, is a #1 USA-ranked age 55-59 high jumper, and former national champion and #3 world-ranked professional triathlete. He lives in Lake Tahoe, Nevada with his wife, Elizabeth, and enjoys a daily cold plunge in the lake year-round.