Waking up at the crack of dawn and going for a run might feel intimidating when you start trying to make it a habit. Weaving a significant new activity such as this into your regular routine obviously takes determination and time—but how much time is really needed to make that habit stick?
One popular idea suggests that it takes 21 days to solidify a habit. A three-week time frame might sound easily reachable to someone making a resolution on New Year’s Day, when people tend to feel extra motivated to start a new habit or kick an old one, says Colin Camerer, a behavioral economist at the California Institute of Technology who has conducted research on habit formation. Yet every January 21 very few people can boast that they have kept their resolutions. One survey showed that only 9 percent of people actually stuck to their goals in 2023.
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Everyone has a unique habit-building timeline—and no matter how long it is for any individual, repetition is the key to making it work, explains Phillippa Lally, a senior lecturer in psychology and the co-director of the Habit Application and Theory group at the University of Surrey in England. Both Lally and Camerer suggest various individualized ways to reinforce healthy behaviors and to eventually turn a wholesome task into an unconscious habit.
Habit formation can range from a few weeks to a couple of months
The origin of the “three-week theory” has nothing to do with habits, per se. It apparently originated from the 1960 self-help bookPsycho-Cybernetics, in which plastic surgeon Maxwell Maltz observed that it took his patients about 21 days to get used to their new appearance after surgery. No formal experiment was conducted to verify this, but the book applied this 21-day timeline to self-transformation in many other wide-ranging aspects of life. For instance, the book also set three weeks as the time needed for people to get used to a new house or change their mind about their beliefs.
Even without much solid research, the 21-day myth became widely accepted. It likely persisted because it seems like such a reasonable amount of time, Camerer explains. Establishing a regular exercise habit in just three days feels seems too quick and implausible, for example, and a year seems too long and daunting. Camerer says people might easily see 21 days as a realistic and achievable time frame.
Almost a half century later, researchers finally gathered strong evidence that countered this idea. A hallmark 2009 study on habit creation found that habits developed in a range of 18 to 254 days; participants reported taking an average of about 66 days to reliably incorporate one of three new daily activities—eating a piece of fruit with lunch, drinking a bottle of water with lunch or running for 15 minutes before dinner. Consistent daily repetition was the biggest factor influencing whether a behavior would become part of an automatic daily routine, says Lally, who was the first author on the study.
The type of activity is also a factor. Teaching yourself a completely new skill or process obviously takes longer than remembering to drink more water in the morning, Lally notes. A 2015 study found that new gym-goers had to exercise at least four times a week for six weeks in order to develop an exercise habit. And last year Camerer and his colleagues conducted a study that used machine learning to determine the time needed for habit-building. In it, machine-learning models analyzed vast amounts of data on repeated observations of a behavior and factored in different variables that may influence a person’s decision to continue the behavior. The results showed that creating a handwashing habit took a few weeks, compared with the half year it took for people to develop an exercise habit. Handwashing, the study noted, is less complex than exercising and offers more opportunities to practice. The researchers also suggested that habit formation depends on the effort that a person puts into practicing an activity and on the presence of environmental cues that would remind them to carry out the behavior.
How to maintain consistency when forming good habits
When it comes to keeping a resolution, Camerer notes it can be hard to stay motivated once the initial excitement of a “new year, new me” wears off. This can easily lead to lapsing or even dropping the activity completely after a couple of weeks. Creating a specific plan to perform the activity (for example, “study Spanish grammar for 20 minutes three times a week” versus the vague goal “learn more Spanish”) and having some type of accountability (an app tracker or a friend) can help monitor progress and push a person to keep going. Additionally, people are more inclined to keep a resolution that they are interested in doing, rather than one that they simply believe they should do.
Rewards are great motivators but only when they’re given right away. Lally says that people often make the mistake of delaying gratification—for example, by treating themselves to a shopping trip on Saturday after going to the gym all week. A reward is far more effective if received during the task. For instance, a person with an exercise goal could watch a newly released movie while running on the treadmill instead of waiting until the end of the week. Researchers in 2014 had people listen to then popular audiobooks (such as the Hunger Games trilogy and The Devil Wears Prada) that could only be accessed at the gym during the experiment and found that the participants initially went 51 percent more frequently than the control group.
Another tip Lally recommends is pairing the desired behavior with a reliable cue. For example, if a person goes to the office two days a week, scheduling gym sessions right after work reinforces an association that trains the brain. The more you relate the two behaviors, the stronger the resulting neural connections in brain regions involved in memory and habit formation.
Reconfiguring your physical space may also help. If your goal is to eat more fruit, for instance, Lally says you are more likely to do it if you keep a variety of fruits stocked and on display in your house. This also applies to breaking habits. People partaking in “Dry January” may empty the liquor cabinet beforehand to avoid temptation. While this might help temporarily, drug and alcohol addictions require more serious medical intervention and time.
What happens if you miss a day?
Sometimes life happens; it is completely normal to miss a day or two in any new routine. Lally says that people tend to create rigid schedules that require carrying out a desired behavior every day—even when that’s not really feasible. When people cannot meet their own expectations or if the activity itself (such as running 10 miles every day) is too hard, they can be deterred from trying again.
If you feel that you are falling off track, Lally advises taking a beat to evaluate why you are missing days and to come up with ways to fix the problem. Instead of running 10 miles every day, try jogging two miles three times a week. If that’s still too challenging, adjust even more by slowing the pace or shortening the distance, and then eventually work yourself back up to the original goal. Putting on sneakers and walking down the block may not seem like much of an achievement at first, but it’s a step in the right direction.
So don’t kick yourself if you didn’t reach your goal by the 21st of this month. As long as you keep at an activity, you will get better at it—no matter how long it takes.