Born in Drimnagh, he had a successful amateur running career in Ireland that led to a scholarship in the United States, where he won four NCAA titles in track running and ran a sub-four-minute mile to set an Irish record at 22 years of age. He soon set the European record over the distance. His speciality was the indoor mile run – he gained his nickname, "The Chairman of the Boards", as a result of his great success on the US indoor circuit. He broke the indoor mile world record on three occasions, and also set a world indoor record over 2,000 m.