After 25 years of doing radio shows with health experts, Dr. Friedman says there are really just 3 things people want: they want to upgrade their brain, they want to optimize their body and defy aging. 

Ben Greenfield's new book Boundless covers all those bases. He's a human performance consultant, a former bodybuilder and a 13-time author. 

He joins Dr. Friedman to talk about his newest title, finding the best diet for your body with genetic testing, and getting outside (with or without shoes).

Find out more about Ben and his podcast at BenGreenfieldFitness.com