U.S. Air Force Airman 1st Class Vidal Rivera III, 1st Maintenance Squadron low observable aircraft structural maintenance apprentice, executes a specialized push-up during a physical training session at Langley Air Force Base, Va., Nov. 22, 2011. An intense physical training regimen was developed for the 1st MXS, designed to transform mundane self-paced exercise into explosive, multi-faceted group workouts. (U.S. Air Force photo by Airman 1st Class Kayla Newman/Released)