Seo's passion for acting was ignited during his travels in Europe, where he witnessed street musicians living with pride and receiving positive treatment.

Initially seeking a corporate job for financial reason, he realized the insignificance of wasting time and decided to pursue a career as a theater actor in 1992.

[note 1][4] He spent five years at the Theatre Company Michu, gaining experience in translation, creative writing, and performing in various theater productions.

Director Lee Gwang-mo discovered him through a video of his play, and this unexpected opportunity led to his debut in the film industry with the movie 'Beautiful Days.'

Seo believes that his existence as an actor is a result of establishing his own values, pursuing his long-standing dream, and maintaining a positive outlook on his given circumstances while utilizing them to his advantage.

[8] A year later, the National Theater Company of Korea and German director Jens-Daniel Herzog collaborated again in Terrorist Hamlet (2008) for NTCK Regular Performance The 210th World Masterpiece Stage.