But in 1990, the compensation and benefits that Korean stuntmen received were meager at best, and Jung was hired only to carry heavy equipment for the stunt acting team on a direct-to-video film he applied for.

Deeply disappointed, he temporarily quit stunt work; instead, every day he underwent intensive exercise at Boramae Park to improve his physical strength, and continued learning various martial arts such as aikido, hapkido, kickboxing and fencing under Kim Young-mo at a nearby training center from 11 p.m. until dawn.

He was responsible for designing the street shooting in Shiri (1999), the wrestling in The Foul King (2000), the western spectacle in The Good, the Bad, the Weird (2008), and the hand-to-hand combat and wire work in The Berlin File (2013).

[4][5] Jung listed Park No-sik and Jang Dong-hwi among the Korean action film actors that he respects, saying, "I thought it was very cool to wear a formal hat and throw blows at the enemy and rescue women.

This, and his commitment, passion and pride regarding the action/martial arts filmmaking in Korea are part of the reason he founded the Seoul Action School at a gymnasium in Boramae Park on July 1, 1998.

[8] Besides Korean cinema, Jung was the action director for the 2002 Japanese film Seoul (ソウル) by Masahiko Nagasawa, and the 2007 Russian blockbuster Mongol: The Rise of Genghis Khan (лНМЦНК) by Sergei Bodrov.

[3] Longtime friend and collaborator, director Ryoo Seung-wan has spoken of how he greatly appreciates Jung's stubbornness when providing creative input in his films' action scenes.