You don't need a gym membership to get in a good workout. Bodyweight exercises, which you can do at home or at the park, will do the trick. But economist Allison Schrager argues in a story on Quartz that if you're going to belong to a gym, you should splurge on an expensive one (if you can afford it).
The business model for gyms, especially low-priced ones, counts on many members rarely (or never) showing up. It's human nature to not care about losing $10 per month on a cheap membership. But if you're shelling out $100 per month, you're going to start feeling guilty if you're not going to the gym.
It's not just the fear of wasting money that makes people show up. A 2006 study found people whose companies paid for their memberships to expensive gyms went about as often as those who footed the bill themselves. Luxury and the allure of a high-end product seem to play a role in getting us to find time to work out, regardless of who's paying.