He was growing to the point that, at twelve years old, he had the stature of an adult and was also arrested as a deserter, until his relatives came to explain that he was just a kid wearing adult men's clothes. Still a teenager, driven by poverty, Primo emigrated to France to stay with his uncle, finding employment as a carpenter. The uncles introduced him to the world of boxing, organizing a match with a beginner, but Carnera was not yet ready for the big step. His physique, meanwhile, was still growing: 205 cm tall, 125 kg of weight; he was nicknamed "violin's feet" because he needed size-52 shoes. He could adapt clothes, but was accustomed to walk barefoot.
In 1925, a circus stopped right where he living, near Le Mans. One day, during one of the wrestling matches which he was attending, the manager noticed his imposing physique and hired him. Carnera began touring as a wrestler, and his manager offered a prize for anyone who could defeat him, but none succeeded. He became a freak and were saddled with nicknames, including the curious "Juan the Spaniard".
One day the circus made a stop at Arcachon. Here, among the crowd, there was also Paul Journée, a former French heavyweight champion who saw in his exceptional ability the potential of a boxer. But training for Carnera would mean abandoning the circus and return to poverty, and thus at first he chose to drop the proposal. Later on he found a solution: he would go back to his earlier job, and train in Journée's gym. Thanks to his stubbornness, and the teachings of the former champion, soon he reached good levels. Journée insisted on showing Carnera to manager Léon See, who was stunned by the Italian's impressive size, and organized a couple of matches, one against a heavyweight boxer, that the Friulian knocked out; but then, he apologized for harming him, to the anger of his manager.