Columbu was born on August 7, 1941, in Ollolai on the island of Sardinia, Italy. He was a son of shepherds Maria Grazia Sedda and Antonio Columbu. He said in 1982: "I was always skinny. Until I was 11, I got beat up a lot. Then one day, I started beating people up. Nobody could touch me. " He worked as a shepherd while training as a boxer. He won over 30 fights as a boxer before quitting the sport in favor of weightlifting and bodybuilding, stating: "Boxing's too rough on your face and head. "