Staff Sgt. Brian Sixto, a drill instructor for Platoon 3034, encourages Rct. Edgar Barua-Gomez, Platoon 3034, Mike Company, 3rd Recruit Training Battalion, to respond to orders March 12, 2014, during an incentive training session on Parris Island, S.C. Discipline, defined as the instant and willing obedience to all orders, respect for authority and self-reliance, is a key trait drill instructors like Sixto, 28, from Hobson, Texas, must instill in recruits. Barua-Gomez, 23, from Kensington, Md., is scheduled to graduate May 23, 2014. Parris Island has been the site of Marine Corps recruit training since Nov. 1, 1915. Today, approximately 20,000 recruits come to Parris Island annually for the chance to become United States Marines by enduring 13 weeks of rigorous, transformative training. Parris Island is home to entry-level enlisted training for 50 percent of males and 100 percent of females in the Marine Corps. (Photo by Cpl. Caitlin Brink)