Larry Hartsell began his martial arts training in Kenpo karate with Ed Parker in 1961. He earned a black belt from Parker and went on to earn a black belt in judo as well. In 1967 he started training with Bruce Lee. He served as a military police officer in the army, including combat time in Vietnam. After returning from the war, he continued training at Bruce Lee's school under the guidance of both Bruce Lee and his senior instructor Dan Inosanto. His training included private lessons at the Bel Air home of Bruce Lee. Hartsell continued his training with Dan Inosanto for the next 35 years. Hartsell's research of techniques resulted in additions and innovations to the grappling that now forms the core of the Jun Fan Jeet Kune Do Grappling system.
He obtained a degree in criminology as well as years of law enforcement experience. This, combined with his notoriety had put him in wide demand as a professional bodyguard for celebrities (such as Mr. T), and also as a trainer for the Dallas Cowboys and San Francisco 49ers. Hartsell gave self defense and combat courses to the Navy Seals and police officers through various colleges, agencies and law enforcement training programs.
He has co-authored or authorized several books on Jeet Kune Do and has released seven videotapes on the grappling and combative arts. These books, videotapes and his skill in the grappling arts have resulted in Hartsell being listed in the "Who's Who in Martial Arts" and cover shots with numerous feature articles in Inside Kung Fu, Black Belt Magazine, Martial Arts Training, Inside Karate, Australian Fighting Arts, and many others.