Complex sentence: He was excused from serving in World War II due to heart problems and after a number of films co-starred in "Meet Me In St. Louis" with Judy Garland, as the boy next door she is set on meeting.
Split into simpler sentences: He was excused from serving in World War II due to heart problems. After a number of films, he co-starred in "Meet Me In St. Louis" with Judy Garland, as the boy next door she is set on meeting.