Self-control is something that we all struggle with. Despite our best intentions, we are often unable to follow through on behaviors we know are valuable (e.g. exercise), and cut down on other behaviors we know are a harmful or a waste of time. These self-control problems are frequently at the root of some of our most persistent personal, public health, and economic issues.

Members of a university gym were given the opportunity to select four audio novels to put on a loaned iPod. The iPod was then kept in a locker for their personal use, such that gym members could only use the iPod while at the gym. Participants were encouraged to exercise more than they had before, and were read the following script:

“In order to make each workout you engage in at [university gym’s name] gym more tempting (so that after a long day, you will actually find yourself craving a workout rather than dreading one), we will only let you enjoy these novels while exercising at [university gym’s name]. The iPod we are loaning you during this study will be required to remain in a locker at [university gym’s name] at all times when you are not checked into the gym facility, and study administrators will check the locker regularly to ensure compliance with the study protocols.

The hope is that you will frequently find yourself longing to find out what happens next in your novel, and this will lead to trips to the gym to satisfy that curiosity. Before long, we hope you will find yourself exercising more regularly as a result of your audio-novel addiction.”

Another group of participants were given a similar opportunity, except that instead of being restricted to using the iPod in the gym, they were only strongly encouraged to restrict their listening to the gym. Both programs lasted nine weeks.

A randomized evaluation found that, during the first week of the program, participants who could only listen to the audiobooks while at the gym went to exercise 51% more frequently than other study participants (estimated 1.42 compared to 0.94 visits/week). The other participants formed two groups: one that got to store audio books on a personal iPod and received encouragement to restrict listening to the gym, and another group whose members received an equal-value ($25) gift card to a bookstore.

Gym members who were encouraged rather than required to restrict their audiobook use to the gym increased their visits to a lesser degree, by 29% in the first week (estimated 1.21 compared to 0.94 visits/week). However, these effects reduced over the nine-week study period until there were no differences between groups, which is consistent with other research on improving exercise habits. Bundling audiobooks with gym attendance boosted exercise rates more for people with busier schedules, and for those who reported enjoying their first workout more than average.

Inspired to implement this design in your own work? Here are some things to think about before you get started:

• Are the behavioral drivers to the problem you are trying to solve similar to the ones described in the challenge section of this project?
• Is it feasible to adapt the design to address your problem?
• Could there be structural barriers at play that might keep the design from having the desired effect?
• Finally, we encourage you to make sure you monitor, test and take steps to iterate on designs often when either adapting them to a new context or scaling up to make sure they’re effective.

Additionally, consider the following insights from the design’s researcher:

• Temptation bundling works with two behaviors that have complementary self-control problems: one behavior people want to do because it’s instantly gratifying and one they know they should be doing because of long-term benefits.
• The behaviors must be able to be bundled, such that they can be carried out simultaneously or one can’t be done without the other.
• Encouraging individuals to enforce the restriction themselves is somewhat effective, but external enforcement of the restriction works best.
• The effect of the bundling is strongest at first and can fade over time, especially after breaks in peoples’ routines such as a holiday or vacation.

For more guidance on implementing this design, choose “I want to try this” from the left drop-down menu.