U.S. Marine Sgt. Katheryn Swingle, drill instructor,

U.S. Marine Sgt. Katheryn Swingle, drill instructor, Oscar Company, 4th Recruit Training Battalion, Recruit Training Regiment, Marine Corps Recruit Depot Parris Island, conducts incentive physical training to instill order and discipline during the first phase of recruit training aboard Marine Corps Recruit Depot Parris Island, S.C., Oct. 29, 2012. Incentive physical training consists of rigorous exercises such as Marine Corps push-ups, mountain climbers, side straddle hops, and crunches. (U.S. Marine Corps photo by Cpl. Aneshea S. Yee/Released)