U.S. Navy Adm. William McRaven, commander of U.S. Special Operations Command, visits with Capt. Ron Knight, chief of the 1st Special Operation Wing Safety while using the anti-gravity treadmill, Jan. 30, 2012, at the 1st Special Operations Medical Group physical and occupational therapy clinic on Hurlburt Field, Fla. (U.S. Air Force photo/Senior Airman Eboni Reams)