U.S. Air Force Senior Airman Brian, 45th Intelligence Squadron, and James, 30th Intelligence Squadron, complete a portion of the Tough Mudder challenge at the Peacemaker National Training Center in Gerrardstown, W.Va., Oct. 20, 2013. The purpose of the challenge, which is not timed, is to test all-around strength, stamina, mental grit and camaraderie of competitors, according to the event’s website. (Courtesy photo/Released)(Llast names withheld for operational security purposes)