Complex sentence: Chopra did not at first apply for a license to practice medicine in California, preferring to teach and write; he regained his "M.D." by getting a Californian medical license in 2004.
Split into simpler sentences: Chopra did not at first apply for a license to practice medicine in California, preferring to teach and write. However Chopra regained his "M.D." by getting a Californian medical license in 2004.