Lauren Adamson was holding on tight to her holiday weight. Her five sisters were, too, baking delicious treats after the holiday season was over. The Utah natives craved a fun way to motivate each other to lose those pesky pounds. So, they pulled out their wallets.

But the sisters knew that just ponying up for gym fees wouldn’t do it. Sixty-seven percent of people with gym memberships don’t use them, according to the Statistic Brain Research Institute. Memberships can cost $58 on average, the Institute said, and if they go unused, that money adds up quickly.

Instead of watching money go down the drain month after month, there may be a way to put cash back in your wallet by exercising. According to a Mayo Clinic survey in 2013, the average weight loss for financially motivated people was 9.1 pounds, while the group with no money on the line only lost 2.6 pounds on average.

Here are three ways you can use money to motivate yourself to exercise:

Put money where your exercise shorts are

If betting money frightens you, apps like StickK and Pact will get you motivated. These programs are tooled to help people make their vices more expensive. “How do you increase your vice?” Cofounder of StickK app Dean Karlan answers, “Make it so failing to achieve your goal is costly.”

StickK helps you reach your goals with commitment contracts, a pact you sign with yourself to guarantee you’ll succeed. Your contract asks that you put your own money down as an incentive to work out. Once you’ve done that, a ‘referee’ on the app will verify that you’ve done the work. If not, the money comes directly out of your bank account on file. StickK’s team has found financial risks triple the chance of success. “It’s based on science,” Dean tells MiLLENNiAL. “It’s randomized trials for healthy behavior.”

StickK has seen multiple studies where treatment groups use the app and the control group doesn’t. The treatment group loses more weight. Similar app Pact works the same way as StickK in the beginning: you put money on the line, but if you’ve met your goal at the end of the week, you get paid by Pact users who didn’t.

Make weight loss a family activity

If you’re motivated by friends and family, make it a game. Lauren Adamson and her five sisters motivated themselves to lose weight as a team after posting an eight-week challenge on their Six Sister’s Stuff blog. “It was so much easier when we were keeping each other accountable and we put some money on it,” Adamson tells us. “We did whoever lost the most weight and whoever earned the most points.”

The six sisters each threw in $20. Each week, they’d gather points by drinking 64 ounces of water, eating fruits and vegetables, skipping sugary treats six days a week, keeping a food journal and exercising 45 minutes a day five days a week. Each week they met their goal, they won five points. They also earned 10 points every time they lost a pound.

“We had a super fit sister,” Adamson says. “She didn’t have a whole lot of weight to lose, but she got the most points.”

The sisters still living in Utah found work out classes together. For those that lived out-of-state, there was the sister group chat, where they would win points by offering encouragement through the forum.

“It’s good to have contact with a team mate with a text saying, ‘You’ve got this!’, ‘Go to the gym’ or ‘What did you do to work out today?” Adamson adds. “It was fun to know we had each other even though we were competing against each other.”

The sisters completed the challenge four years ago, but they still motivate each other today. They continue to pass the challenge along to groups of coworkers, high schoolers and other families.

“Even though the blog post was written in 2012, we still get emails everyday,” Adamson says. “It’s still a big hit and it’s because of the support people give.”

Move for the cause

If you’re motivated by helping others, programs that donate money based on your movements could do the trick. The Charity Miles app donates money every time you move. You start by selecting a charity. “We have charities from cancer to animals to maternal health issues,” Digital Marketer for Charity Miles Lauren Theurkauf tells us. “There’s a cause for everyone.”

Once you choose the one you’d like to support, you select your activity: walk, dance, run, crunches. “And as you move, it donates,” Theurkauf explains.

Before you start moving, you have to select indoor or outdoor, so your phone knows how much money to donate. “In outdoor mode, it uses a GPS on your phone,” Theurkauf says. “If you do indoor mode, it uses an accelerometer hardware in your phone, an algorithm that knows how many miles you’ve actually traveled.”

Millennial Magazine - weight

In order for it to work, it needs to be on your wristband or in your purse, but just make sure you have it on you.

Experts find apps like Charity Miles are a great form of motivation. “It helps them not only exercise at all, but then go the extra mile for that charity to make the biggest impact they possibly can,” Stephanie Bagley, SVP of business development & operations at Charity Miles, adds.

Putting money on the line is an interesting way to get back in the gym you’re paying for and lose a couple pounds while you’re at it. But money is an extrinsic motivator, says Anthony Kontos, assistant research director for the University of Pittsburgh Medical Center Sports Medicine Concussion Program. “It can be effective in getting somebody sedentary and skeptical of exercise to the ball part, so to speak.”

But if you want to keep weight off, Kontos says, exercise needs to become an intrinsic motivator, a part of your lifestyle. “There in lies the challenge,” he suggests. “The term exercise is viewed negatively. Re-imagine it as something you enjoy and are passionate about. Make it fun. And make it on a regular schedule. Something that might be considered a routine will become second nature.”