Ganz grew up in Queens, New York and graduated from Martin Van Buren High School in Queens Village. He briefly attended Queens College, City University of New York, where he and his friend Mark Rothman wrote several comedic skits and shows for school productions. After Rothman's father Abe—a chauffeur who sometimes drove for The Mike Douglas Show—was able to pass a spec script of theirs to Tony Randall, the two got a try-out writing gig on Randall's hit TV show "The Odd Couple". However, the producers of the show would only pay for them to come to Los Angeles one-way. Ganz and Rothman dropped out of college and headed west to take the job. After being fired—causing them to briefly live in their car and contemplate driving back across the country to New York—and then re-hired by producer Garry Marshall, the two became regular writers on the show; and Ganz eventually became Head Writer.