What was your favorite childhood book growing up when you were first learning how to read? That might say a lot about you and who you are today! So says one of the contributors to Tim Ferriss' great new book, Tribe of Mentors. Dr Rubin picked "The Lorax", signifying his commitment to the healthcare of the kids. If you held that last seed in your hands, would it survive? Would new trees grow because of you? What's your favorite children's book and why?