She used VCR machines to sell her exercise dance routines to paid instructors across the country. She also wrote a very popular book called Jazzercise: A Fun Way to Fitness, in 1978. Throughout the 70's and 80's more aerobic fitness stars emerged such as Martha Rounds, Debbie Rosas, Nancy Strong, and Gilda Marx.[23] They spread aerobic exercises like dance aerobics to women across the United States.