Jigoro Kano
As a young boy, Jigoro Kano - son of a medical doctor - found himself victim to bullying at school and so he chose to learn Jujitsu to strengthen his small frame and learn self-defense. Eventually he went on to developed a new theoretical and technical system based on the concept of “maximum efficient use of physical and mental energy” that in 1882 became known as Kodokan Judo.
From kicksport.com