The purpose of this study was to identify the effect of systematic mental skills training (MST) for a taekwondo gold medallist. Based on MST of other sports, this programme was designed for a single subject who competed in the Olympics. The Korean test of performance strategies, Sport Attributional Style in Korean Athletes, and a few sessions of interviews were applied to investigate the effect of MST. The pre and post-test mean scores of both the Korean test of performance strategies and Sport Attributional Style in Korean Athletes were compared. Interviews recorded the athlete’s psychological characteristics. Excluding the ‘activation’ variable, all of the psychological skills, e.g. self-talk (4.25–5), emotional control (3.75–4.5), automaticity (3.75–4.25), goal setting (4.5–5), imagery (4.25–5), negative thinking (3.25–4.75), anxiety management (4.5–5), and physical and mental condition (4.5–5) improved. MST is believed to have helped the athlete succeed.