Lt. Col. (Dr.) Joseph Huseman, 21st Medical Squadron Aerospace Medicine Flight commander, checks the heartbeat of Airman 1st Class Lucas Bracken, 21 MDS, at the Schriever clinic March 23, 2017. March 30 is National Doctors' Day, which is an opportunity to celebrate those who've dedicated their lives to healthcare. (U.S. Air Force photo/Senior Airman Arielle Vasquez)