After medical school, Dr. Colburn completed an internship at Kettering Memorial Hospital followed by an internal medicine residency at Loma Linda University Medical Center and Riverside General Hospital. He then continued his medical training as a rheumatology fellow at UCLA and Sepulveda VA Medical Center. After his fellowship, he returned to Loma Linda University (LLU) to begin his career as an assistant professor of medicine. Dr. Colburn also served as chief of rheumatology at Jerry L. Pettis Memorial VA Hospital and LLU for over 20 years as well as associate chair for research in the LLU Department of Medicine. He is currently working as professor of medicine at LLU.
Throughout his career, Dr. Colburn has served in various leadership roles and has been a member of numerous committees. He and his wife, Janine, currently reside in Yucaipa, California, and they have two sons, Jeffrey and Jonathan.