Japanese Air Self-Defense Force members help each other equip their oxygen tanks as they prepare to run 110 flights of stairs at Yokota Air Base, Japan, September 11, 2020. During the 9/11 Memorial Tower Run, teams of four relayed to run 110 floors together, simulating the floors first responders would have had to climb after the attacks. (U.S. Air Force photo by Staff Sgt. Kyle Johnson)