Complex sentence: He made his film debut in Judd Apatow's "Knocked Up" as Dr. Kuni, which proved to be his breakout performance from that point forward he was able to transition from medicine into a full-time career in the entertainment industry.
Split into simpler sentences: He made his film debut in Judd Apatow's "Knocked Up" as Dr. Kuni, which proved to be his breakout performance. From that point forward he was able to transition from medicine into a full-time career in the entertainment industry.