Making a design that is really welcoming is one of these tricks. Modern gyms resemble hotels or bars more than the traditional, warehouse-style gyms of the past when we first saw men like Arnold Schwarzenegger getting swole.
They have upscale, cozy lounges (sometimes multiple), juice bars, snack shops, gift shops, and a variety of other luxuries that have nothing whatever to do with working out. All of this works to draw in the kind of customer who considers themselves casual fitness enthusiasts but is almost probably not one. Gym memberships are an example of what behavioral economists refer to as “pre-commitment,” whereas people generally dislike being locked into something (like cell phone contracts), we actually tend to prefer being locked into a gym membership because we start imagining the newer, fitter version of ourselves a few months down the line. According to the number of dropouts and no-shows at most gyms, it just needs a degree of discipline that the majority of people simply don’t possess.