Owen began to box at the age of eight, idolising fellow Merthyr born boxer Jimmy Wilde. Along with his siblings Vivian and Kelvin, in the spring of 1962, he joined the Merthyr Amateur Boxing Club housed in a small hut on nearby Plymouth Street. Broadbent describes how, by age ten, Owen developed "some rudimentary ring craft and already had the boundless energy that would be his signature ... His punches were light but his effort huge." Owen and the other members of his club travelled the country, competing against youth clubs from Wales and England. Each year culminated in the Welsh amateur championships, a junior event which stipulated that a fighter must have gained each year they entered. Martyn Galleozzie, who trained alongside Owen, noted how Owen struggled to achieve the weight increase each year and was fed cakes and biscuits on the journey to try and make weight. Galleozzie also stated how his mother once sewed lead into the lining of Owen's shorts to make weight.