Myhrum began his career in the theater, and became interested in television after watching the broadcasts of the Army-McCarthy hearings in 1954. Myhrum started out as a mail clerk at CBS, and worked his way up to becoming a director. Besides his children's TV work on Captain Kangaroo and Sesame Street, Myhrum also had a long career directing soap operas, including The Doctors, Love of Life, The Secret Storm, Ryan's Hope, Days of Our Lives and As the World Turns.