24 Hour Fitness began in 1983 as 24 Hour Nautilus, a one gym company founded by Mark Mastrov and Leonard Schlemm.
Mastrov hired Mark Golob to market the club. Golob created commercials with Pamela Anderson, Arnold Schwarzenegger, and Mike Tyson.
By 1994, there were 32 clubs. The company acquired Family Fitness Centers and renamed to 24 Hour Fitness after an investment by McCown De Leeuw.
In 1997, the company expands to Europe after a failed IPO attempt.
In 2000, 24 Hour Fitness Worldwide is created as a holding company.
In 2005, the chain is listed for sale. It eventually sells to Forstmann Little & Company.
In 2007, the chain was subject to a class action lawsuit by 1.8 current and former members who claimed funds were still ACH withdrawn from their accounts after they had canceled their memberships.
The company was also hit with big fines in late 2017 after a court found that members were deliberately misled when signing up for contracts.
Today, 24 Hour Fitness is the world’s largest privately owned fitness chain. The company has over 420 clubs in 18 states and serves more than 3 million members.