NEW YORK (TheStreet) -- You won't find jacked, sweaty bodybuilders pumping iron at Planet Fitness, nor will you find skinny folks sipping drinks from the juice bar. That's by design, according to Dorvin Lively, CFO at the rapidly growing gym chain.

Planet Fitness was founded by Mike Grondahl in 1992 as a welcoming place to work out at prices more affordable than upscale competitors Lifetime Fitness (LTM) and Town Sports International (CLUB). The business attracts people who have never gone to a gym before, benefitting from the movement by the general population toward a healthier, more active lifestyle. The U.S. has 32,000 health clubs, according to industry research firm IHRSA. More than 62.1 million Americans used a health club in 2013. Since 2008, U.S. health club memberships have risen 16%, with growth clocking in at 5.3% in 2013.

Planet Fitness has more than 800 locations in the U.S., which see some 4 million workouts a week from base members who pay $10 a month, and Black Card members that shell out $19.99 for perks ranging from unlimited tanning to being allowed to bring a friend for free.

"From a system-wide base, total sales for 2013 were $890 million," Lively said in a recent interview. Lively said Planet Fitness has "tripled the number of clubs in the last five years (it opened 149 clubs in 2013) and has intentions to "open more than that this year."

What you won't get from the company's catchy television commercials is the fact that many Planet Fitness locations moved into spots vacated by large box retail stores, such as stores once operated by Office Depot  (ODP), which merged with OfficeMax, and Staples (SPLS). Lively said "existing franchisees are committed to open 1,000 clubs," many of which will be in a 20,000-square-foot model. The closed big box stores offer a turnkey venue for those new sites.

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