Photo: Andrew H. Walker/2013 Getty Images

The latest annual filing from Town Sports International, the company that owns New York Sports Clubs, reported the company had 627,000 members who made approximately 30 million visits in 2018. That is, the average member visited just under once a week; averages working as they do, the median member almost surely visited even less frequently.

The best kind of customer a gym can have is one who buys a lot of personal training, but the second-best kind it can have is one who dutifully pays his monthly fees but rarely or never visits. And that creates an odd incentive if you own a gym: You need to find a way to attract customers who are not especially eager about your product.

As such, discount gym Planet Fitness announced this month it had commissioned a survey finding that six-pack abs are out and the “dad bod” is in. “Both men and women associate the body type with positive traits,” the survey says. This is in line with the company’s “Judgment Free Zone” marketing strategy, which positions Planet Fitness as the gym for regular people, not gym-obsessed “lunks.” It’s the gym that gives away free pizza and bagels. In 2010, an article in Men’s Health called it “the worst gym in America.”

Planet Fitness doesn’t sell personal training, so unlike other gyms, it doesn’t have a good way to make extra money from highly engaged customers. And Planet Fitness is cheap: just $10 a month, or $22 if you want a membership that lets you go to multiple locations. (Planet Fitness’s annual filing says the industry-average gym membership fee is $61 per month.) So Planet Fitness has exactly the sort of membership fee a person might keep paying, even if he or she hasn’t been to the gym in months, with the hope of finally going tomorrow.

And people do believe they will go to the gym in the future more than they have in the past. A 2006 study published in the American Economic Review found gym members estimated they would visit about twice as frequently as they actually did, and that they waited an average of 2.3 months from their last gym visit to finally cancel their memberships. In many cases, infrequent visitors would save money by dropping their monthly memberships and paying a per-visit fee. But that would require admitting to themselves how infrequently they are going to the gym.

Unlike Town Sports, Planet Fitness does not report the total number of annual member visits, so it’s not possible to estimate the average frequency of use by members. But an ingenious aspect of Planet Fitness’s rock-bottom monthly fee is that the membership is barely worth canceling if you even slightly believe you might work out again in the medium-term future.

And that’s an upside of being the gym for people who don’t really like the gym: You don’t even really need to pretend to encourage your customers to work out more frequently. After all, you don’t actually have to go to Planet Fitness to work on developing your dad bod.