Senior Airman Stephen Caseman, 8th Maintenance Group weapons standardization technician, demonstrates a barbell squat at the Kunsan Fitness Center, Kunsan Air Base, Republic of Korea, June 12, 2015. According to Bill Goins, 8th Medical Operations Squadron health promotions coordinator, Airmen should strength train two to three days a week per muscle group; with two to three sets of eight to 12 repetitions [regardless of gender or fitness level], starting with the largest muscles first. (U.S. Air Force photo by Senior Airman Katrina Heikkinen/Released)