Yoo quietly enlisted for his mandatory military service as a regular soldier on 5 March 2013, reportedly working as a trainer of new recruits. He drew praise for doing so at age 19, as majority of Korean men choose to carry out their army duty shortly after high school or during university, unlike most male Korean celebrities who choose to delay their enlistment until they turn 29.Yoo was discharged on 4 December 2014.
