Walking nine-plus hours a day for about 110 days in a row is, to understate it drastically, seriously tough. Add to that the fact that Saunders and L'Herpiniere will each be dragging a provision-laden, 440-pound sled behind them rockets the challenge to insanity levels. To prepare for it, the two have had to up their weightlifting to world-class level. "It's nearly 70 marathons back to back," says Saunders. "So as far as athletic challenges and ultra endurance, it's Iron Man or Tough Mudder times a thousand."

Getting to the necessary level strengthwise was challenging for Saunders, who needed to build up muscle mass without cutting back on his cardio conditioning. He accomplished that by finding a way to push himself in the gym harder than he ever had before. "I normally have two or three heavy-lifting sessions a week," he says. "Real, kind of, power lifting – squats, dead lifts, that type of thing – but trying not to get too big and muscular, because we want to keep the endurance and the efficiency as well." In the end, Saunders could dead-lift three times his body weight – good enough for him to automatically qualify for most sanctioned weightlifting competitions.