After graduating from the University of Illinois at Urbana-Champaign in 1997, Larsen worked briefly as a radio producer and on-air contributor at AM1000 in Chicago for Steve Cochran and Kevin Matthews. Larsen then adopted the on-air name 'Lars Christiansen' and worked as a disc jockey and promotions director for 106.7 the Fox in Decatur, Illinois, leaving in 2001 to work at 95 WIIL ROCK where he appeared during every daypart. In August 2006, he signed on as anchor of the AM1050 WLIP afternoon news program while continuing with evenings on 95 WIIL ROCK. From 2009-2011, he taught English at Grayslake North High School.