Complex sentence: During his childhood, an unknown monk initially inspired him to learn martial arts he later joined Seoul Moo Duk Kwan central gym and began to study under Hwang Kee, a founder of the Korean Moo Duk Kwan system.
Split into simpler sentences: During his childhood, an unknown monk initially inspired him to learn martial arts. He later joined Seoul Moo Duk Kwan central gym and began to study under Hwang Kee, a founder of the Korean Moo Duk Kwan system.