Prior to coming to America from his native country Bulgaria, Stefan spent several years as the National-Team member for his country. He started gymnastics in 1952 and competed for the National Team from 1965 to 1975. During his glory he took part in many national and international competitions. He was six times the absolute champion of Bulgaria in the highest qualification group Sport Master. Stefan also became four times the Balkans champion for Vaulting, High-Bar, Pommel-Horse, and Rings. In one of his best accomplishments he became the All-around Champion in the international championships of the DINAMO organization, where he competed against the Russian, German, Hungry, Romania, Pollen, Korea, Vietnam, and the Czechoslovakian teams. He also participated in five European Championships in the years 1967, 1969, 1970, 1971, and 1973. In 1970 and 1974 he was a participant at the World Championships and participated in the 1968 and 1972 Olympic Games in Mexico and Munich. In his 17 years of competition he accumulated nearly 250 medals.

After completion of his active competition activity in 1975, Stefan began coaching several teams. In 1991 he trained the Junior National Team of Turkey. He graduated his higher education in 1966 at the Higher Institute of Physical Culture G. Dimitrov in the specialty of Sport Gymnastics. Stefan has also served as an International Judge approved by F.I.G. for four years. Stefan began his stay in the United State in 1993. Stefan has good sport and technical training and knows the fine points of the methods of training in gymnastics.