Vail began training year around during his junior year at Centennial High School. He then went on to Oklahoma State University where he was the leader of the 2009 NCAA Cross Country National Championship team. Immediately after graduating from Oklahoma State, Vail signed a contract with Brooks Sports. Vail participated in the 2012 Olympic Trials, where he was a top finisher. Vail was also the top American finisher in the 2013 New York Marathon, and at the 2014 London Marathon, where he finished 10th in 2' 10" 57, his personal best.