After spending time growing up in Little Italy, New York, his family then moved to Saint James Place in Totowa, a suburb of Paterson, New Jersey.

However as a boxer he did not have much luck, although that might have been due to the fact he barely had time to train, having to go out to the street and perform many types of jobs to try to help his family make ends meet.

Applicants were required to be at least 18, but he was only 16, so he changed his birth certificate and all his personal information and they accepted him, believing that he had been born in 1920.

He went back home in 1944 to help run a restaurant and to begin a career as a professional boxer, compiling a record of 6 wins, 10 losses and one draw.

It was here Lou began friendships with Frank Sinatra, Sammy Davis Jr., Frankie Valli, and other celebrities.

Also during that period, Main Events put on boxing cards at the Ice World facility in Totowa, New Jersey.

Dan formed a friendship with Shelly Finkel, a powerful boxing power broker who convinced middleweight contender Alex Ramos, future world light welterweight champion Johnny Bumphus, future world heavyweight champion Tony Tucker, the late light middleweight prospect Tony Ayala Jr. and heavyweight prospect Mitch Green to join Main Events.

He had Bumphus, Lockridge, Bramble and Mike McCallum crowned as world champions, and he signed future world champions Mark Breland, Evander Holyfield, Pernell Whitaker and Meldrick Taylor right after their participation in the Olympics in Los Angeles.

Taylor followed Whitaker and Pazienza by beating Buddy McGirt in 1988 for the world light welterweight title.

Holyfield gave Main Events another championship, when he knocked out Buster Douglas in three rounds to win the world heavyweight title with Duva as his co trainer along with George Benton.

After that, Duva attained mainstream fame, appearing in cameos at different television series and even visiting the "Late Night with David Letterman" show as a guest.

He also acted as wrestler Rowdy Roddy Piper's trainer at the World Wrestling Federation's WrestleMania 2 pay-per-view in 1986; coincidentally, Duva was a distant cousin to WWF manager "Captain" Lou Albano, who had instigated the story line involving Piper.

On the night of the infamous riot after the first Andrew Golota-Riddick Bowe bout, Duva was lifted out of the ring on a stretcher after his defibrillator went off.