After retiring from the NFL, Zimmerman taught and coached at Parlier High School and then Madera High School, both in California. He also was a professional fast-pitch softball pitcher and led his team to 10 world titles over 26 seasons. He was inducted into the International Softball Congress Hall of Fame in 1970 and the award for the outstanding pitcher in the ISC World Tournament is named in his honor. He married Dena Mary Otis of Big Timber, Montana on May 3, 1940, and they had 3 sons. Zimmerman died in Madera, California on August 22, 1997.