Complex sentence: Beginning his medical practice with a residency in San Francisco, he pursued both medicine and writing for several years, leaving medicine in 1998 to join the faculty of the Iowa Writers' Workshop, where he still teaches.
Split into simpler sentences: Beginning his medical practice with a residency in San Francisco, he pursued both medicine and writing for several years. In 1998 he left medicine and joined the faculty of the Iowa Writers' Workshop, where he still teaches.