A head's up if you're thinking about joining a gym for workout motivation.

If the New Year has made you want to reverse the effects of those never-ending Christmas cookies STAT, don’t rush off to join a gym just yet. While hefty discounts on annual memberships may make January seem like the perfect time to join, it's often a waste of money.

That's because as many as 67% of people who sign up for a gym membership never actually use it, according to Statistic Brain. This, unfortunately, is how gyms make money. They count on some members to pay and not show up, NPR reports, and these are their best customers, so to speak. (Watch the video above to learn more.)

If everyone who belonged to one fitness center actually tried to work out at the same time (which is often what a gym feels like in early January), there’s no way they would even fit in the building. Take Planet Fitness, for example. They have a very low membership cost ($10-$20 a month), and have 6,500 members per gym on average, even though most locations could probably only hold about 300 people at once, NPR reports.

While some gyms see a 40% increase in usage in the days after January 1, traffic steadily drops throughout the rest of the year, according to Quartz. The people who continue to use the gym regularly are getting the best deal, at a price partially subsided by the well-meaning members who don't go.

Gyms are even altering their layouts to make the space seem less intimidating to casual gym-goers interested in signing up. For example, instead of walking straight in to an open weight room, companies are installing juice bars and fancy lobbies, while the squat racks are hidden in the back.

So if you're the kind of person who's thinking about joining a gym in order to motivate yourself to work out—you've made a yearlong commitment!—try committing to a regular at-home routine first. If you’re still sticking with it after a few weeks, then signing on the dotted line is less likely to be a waste of your money.