re: What is the best piece of professional advice you’ve gotten from a mentor?

Right before Desert Storm kicked off, our MEU (Marine Expeditionary Unit) commander, Col. Dusty Rhodes, gathered all of us together on the deck of the USS Okinawa. He was a former Vietnam helo pilot with red ink in his logbook so we were expecting a "go win on for the Gipper" speech. He gave us his words of wisdom from his combat experience:

Eat when you can
Sleep when you can
Take a shite when you can

Thus fortified, we went out and flew our missions.