After playing football in his youth, Hary switched to sprinting at age 16. Only a few years later, in 1958, he won his first international title when he came first in the 100 m and the 4 × 100 m at the European Championships. He was also one of the first track stars to be affected by the rivalry between Adidas and Puma; each of the two then-fledgling companies wanted the "world's fastest man" to wear its shoes. Rumors of cash payments were floated, but no evidence was ever found to support the claim.