John was born and raised in Brooklyn, New York into a cop and fireman family. He began college studying aeronautical engineering at Embry-Riddle Aeronautical University in Daytona Beach, Florida. After working at the Brooklyn Navy Yard as a shipfitter off and on over many years, he returned to school attending Herbert H. Lehman College (CUNY) in the Bronx where he discovered acting. He then spent a few years doing regional theater in Seattle before moving to Los Angeles in 1989. He did several commercials, TV guest spots, and small movie parts before being cast as a series regular on Nickelodeon's "The Secret World Of Alex Mack."