A Wharton study on the best ways to boost workout habits

In a new megastudy, lead author Katy Milkman, along with Angela Duckworth, partnered with 24 Hour Fitness to create a 28-day workout rewards program that tested inexpensive, scalable, science-based interventions for building exercise habits among more than 60,000 of its millions of members.

The study, published in the journal Nature, sought to solve motivational problems most people face when it comes to visiting the gym regularly. The megastudy approach to research is a new take on behavioral science, seeking a better way to compel gym attendance by testing many hypotheses at once.

The research tested 53 programs over four weeks at 24 Hour Fitness gyms, where participants’ entries into the gym were recorded. The simplest form of the program encouraged participants to plan their workouts ahead of time, reminded them with a text message 30 minutes before they were scheduled to work out, and offered them points convertible for small cash rewards redeemable on Amazon (these were worth about $0.22 per gym visit, so the researchers call them “micro-incentives.”)

“We’re incredibly excited about the potential of this new way of identifying promising strategies to promote behavior change,” says Milkman, the James G. Dinan Professor at the Wharton School and co-director of the Behavior Change for Good Initiative at Penn, which has pioneered the megastudy approach to behavioral science.

One of the key finding from the study is that 45% of these interventions—ranging from text reminders to weekly emails—significantly increased weekly gym visits by 9-27%.

“Lots of things worked, and our programs were also extremely cheap,” Milkman says. “Most programs tested could be deployed at scale for roughly $0.75 per person per month.” 

The top performing intervention sent gym members who missed a scheduled workout 125 bonus points (or $0.09) on top of their usual micro-incentives if they made it back to the gym for their next planned workout. This led to a 27% boost in gym visits.

“We think this finding is really interesting,” Milkman explains. “It suggests how important it is to avoid having a series of missteps when you’re pursuing a goal. We’ll all slip up from time-to-time, but this simple intervention that discouraged people from letting a single miss accumulate into a streak of failures helped people quite a lot.” 

Another top-performing incentive informed gym members that most Americans are exercising, and that exercise is trending up resulted in a 24% boost in visits.

“The trending norms intervention was developed by our collaborator Robert Cialdini—a brilliant psychologist who has long studied the power of norms to shape behavior,” says Duckworth, the Rosa Lee and Egbert Chang Professor in the School of Arts & Sciences and Wharton who co-directs the Behavior Change for Good Initiative at Penn with Milkman. “The contribution here is that learning that exercise is increasingly popular motivated people to visit the gym more often.”

The megastudy model allows scientists to compare dozens of different behaviors’ change interventions, which can accelerate the development and testing of new insights about human behavior.

The study has helpful insights for those hoping to build exercise into more of their daily lives, but its impact stretches beyond that, according to the researchers.

“We’re really doing two things in this work,” Milkman says. “The first is introducing a new methodology for accelerating the generation of rigorously tested behavioral science insights. The second is learning more about what techniques can be used to encourage physical activity and more generally motivate the pursuit of effortful goals.” 

This kind of study is having important implications for the future, and the method has been used to test the best messages to encourage people to get vaccinated.

“We’re tremendously proud that we’ve been able to leverage the nearly 150 brilliant scientific minds affiliated with the Behavior Change for Good Initiative to help generate key insights about pressing social problems,” says Duckworth. “We hope to continue advancing the science and practice of behavior change for good in leaps and bounds in the years ahead.”