A shared universe › Blog › How long it takes to change a habit · Español
A habit takes quite a lot longer than 21 days to form: in the best-known study, the typical time was around 66 days, with huge differences between people, from 18 to 254. And missing a day doesn’t spoil it. People often say a habit forms in 21 days. Anyone who tries and still finds it hard after three weeks thinks the problem is theirs. It isn’t: that figure doesn’t match what has been measured.
The researcher Phillippa Lally and her colleagues at University College London published a study in the European Journal of Social Psychology in 2010. They asked 96 people to choose something new and simple to do every day, to do with eating, drinking or physical activity, always at the same moment, for example after breakfast. For 84 days they noted whether they had done it and answered a few questions about how automatic it felt.
Of the 96, 82 provided enough data, and for 39 the progress fitted well with the curve used to calculate the result. The time until the habit became nearly automatic ranged from 18 to 254 days. As the study lasted 84 days, the highest figures are a projection of that curve, not days actually counted.
The typical figure from the study was about 66 days. That is how it is summed up by the University of Surrey, where Lally now works, which notes that the result challenged the idea of 21 days and that forming a habit varies enormously from one person to another.
So 66 is not a rule either. It is a reference point so you don’t lose heart if it is still hard after three weeks: that is to be expected.
If you are a month in and still need to remind yourself every day, it isn’t a sign that you are doing it wrong. On what was measured, at that stage many people still needed to think about it.
The study found something else, perhaps more useful: skipping a day did not set people back. The habit carried on forming just the same. What breaks it is not the slip, but giving up after the slip.
Lally explained this years later with her colleagues in a 2012 article for family doctors: after one missed day, progress soon picked up again. That said, the study itself found that people who repeated the behaviour more consistently followed the curve better. Consistency helps; perfection isn’t needed.
The 2012 article sums up the central idea as repeating an action consistently in the same context, and suggests choosing a time and place that come round every day of the week. The more closely the action is tied to that cue, the less it will depend on each day’s willpower.
It can help to write it as a simple plan, “after this thing I already do, I will do this other thing”, and leave it where you can see it for the first few weeks. At first it is normal to need reminding; with repetition, the cue starts to pull the action along almost without your trying.
Stopping smoking, drinking or doing something that harms you is harder and often needs help. Asking for it is not a lack of willpower. Your GP is a good place to start.
With these habits, a stumble doesn’t have to wipe out all the progress, and trying again after a relapse still counts.
And meanwhile, every small step counts. If it helps to see it that way, there is an article on small steps.
In A shared universe you can light a star with that change you want to make, with “What I hope for”, and come back to tell how it is going. Knowing that someone has read it gives you a little push.
Your star will shine for seven days. If you want it beside you while the habit settles in, you can come back and keep it shining for seven more.