Secretary Jim Mattis has earned himself some colorful nicknames over the years. He's sometimes referred to as "Mad Dog" (even though he totally hates that one) or "Chaos," and since he's known to be a deep military thinker who's never been married, many know him as "Warrior Monk."
Benjamin Franklin nailed it when he said, "Fatigue is the best pillow." True story, Benny. There's nothing like pushing your body so far past exhaustion that you'd willingly, even longingly, take a nap on a concrete slab.