Prior to the 2010 Winter Olympics, Mo won two distances at the 2006 World Junior Speed Skating Championships.

Mo started skating when his father suggested it while he was in third grade at Eunseok Elementary School.

Since then, Mo has been a close friend to Lee Seung-hoon, a fellow speed skater who also won a silver and a gold medal from the 2010 Winter Olympics.

[4] As Mo grew older, he almost gave up skating but, after three years of indecision, he decided against giving it up on the advice of his mother.

[5] Mo's first event was at the 2005 South Korean Single Distance Championships, which occurred on 23 and 24 November 2004.

[9] Mo qualified for the 500, 1000 and 1500 m events at the 2010 Winter Olympics, and was an alternate for the men's team pursuit.

[2][10][14] Park Pil-soon, head of the Korean Olympic Committee's international affairs department commented, "Mo was an unknown, and his gold medal win marks the start of a new generation in South Korean speed skating after Lee Kyou-hyuk.

[14] President Lee Myung-bak sent a message congratulating Mo, calling him a "proud treasure who rewrote South Korea's speed skating history", and said that he brought jubilation to the South Korean people with his strong spirit and excellent skills.

After the race, he personally reacted by stating that he "only imagined and dreamed about it" and saw it as a warm-up for his main event, the 1000 m.[16] He received a warm welcome when he returned to Korea, and his parents greeted him with a homemade banner.