Herschel Walker, Heisman Trophy recipient and mental health advocate, speaks to active-duty U.S. Service members, retirees and others about mental health and his career at Langley Air Force Base, Va., Sept. 17, 2014. Walker spoke about how having dissociative identity disorder played a part in his life. (U.S. Air Force photo by Airman 1st Class Breonna Veal/Released)