He is the creator of Jeet Kune Do

In 1967, Jeet Kune Do first appeared. Lee founded The Jun Fan Gung Fu Institute while he was bereft of a job following the filming of a season of The Green Hornet. The contentious match with Wong Jack-man had an impact on Lee's martial arts philosophies. Lee came to the conclusion that the fight had carried on too long and that he had not been able to use his Wing Chun techniques to their fullest ability. According to him, conventional martial arts techniques are too formal and stiff to be practical in chaotic street combat scenarios. Lee made the decision to create a system that was "practical, flexible, quick, and efficient." He began experimenting with varied training regimens, including weightlifting to increase strength, running to increase endurance, stretching to increase flexibility, and many other things to which he was continuously adapting, such as fundamental boxing and fencing skills.

Lee places a strong emphasis on his "style without style." This entails getting rid of the codified method, which Lee views as a manifestation of the conventional style. Lee later transformed the system into a philosophy and martial art he would call Jeet Kune Do or The Way of the Intercepting because he believed even the method he now refers to as Jun Fan Gung Fu was too constrained. Fist. He would eventually come to regret using the phrase Jeet Kune Do since he believed that martial arts should exist without boundaries and within style-specific limits.'