Kellen got his start in a full sized car racing in 2001, where he quickly proved he has talent to get to victory lane. In his first A Main he qualified for in a Dirt Modified, he won at the age of 16. He added a rookie of the year that same year.
Kellen has overcome some tough challenges during his racing career. In 2008 (age 21) he suffered serious injuries while racing in Arizona, including fractures to bones in his neck and back. Although the doctors were not sure if he would even walk again, Kellen showed his toughness and told the doctors he would race again. After spending 6 tough months of mending up, rest and rehab, Kellen jumped back into race car, determined to do what he loves-Race.