Born June 4, 1967, in Killeen, Texas, Kimbrough attended the Lovett School in Atlanta, Georgia, graduating in 1985. Kimbrough graduated from the United States Military Academy in 1989 with a B.S. in aerospace engineering. He played for the West Point baseball team for 4 years, and was selected as team captain his senior year Army Black Knights baseball players.

Kimbrough served as an Apache helicopter pilot in the first Gulf War, Operation Desert Storm in 1991. Kimbrough later attended and graduated from Georgia Tech with a M.S. in operations research in 1998. He helped NASA train astronauts on landing procedures for several years before he himself was selected for training. He retired from the U.S. Army with the rank of colonel.