Jocko Willink: I was very lucky ... When you're going on an operation, the gear that you bring with you is going to vary a little bit, but it depends on what the mission is, not on how dangerous ...

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. Following ...