 Welcome to the disco! Simmons created a fitness empire that lasted more than four decades, with videos, classes, books, products, infomercials, and plenty of TV appearances. And he benefited from a new technology of the 1980s by putting out his classes on VHS cassettes played on VCRs. Here's historian Natalia Melman-Petruzella trying to sum up Simmons in just a few words.