They kept one of Frank Livingston's keys. The drill instructors told him to fasten the other around his neck with a piece of twine. Tight, they said, with no slack. They ordered him to open his locker box without loosening the key chain around his neck. He wiggled and writhed on the ground, angled his neck close enough so that his face could kiss metal, and managed to unlock his belongings. "You just had to do it," Livingston recently recalled over the phone. "I bet I can do it quicker today with the key around my neck than you could with the key around your hand." More than 60 years ago, boot camp in the Marine Corps featured plenty of challenges like this. Like the time tear gas was tossed into his bunk just minutes after he learned how to properly operate a gas mask. The motto became the mind-set: Nothing's impossible in the Corps.