Jocko Willink, a former Navy SEAL commander, host of the "Jocko Podcast," and the author of "Discipline Equals Freedom: Field Manual," explains how he works out to maintain his physique.

Whether you want to build muscle, burn fat, or live longer, some of the simplest exercises are the best place to start, the retired Navy SEAL Jocko Willink says. Willink, a black belt in Brazilian ...