A lot of the change that comes about through a process like psychotherapy (or even just reading a self-help article or book and trying to put those ideas into effect in your life) requires forming new habits. Habits of thinking differently, of reacting differently, of behaving differently. And it can be a frustrating process as you wait for these changes to take effect and become more automatic, as habits do.

How long does it take to form a new habit? A week? A month? A year?

Contrary to popular opinion, most people will not be successful at forming a new habit in their life in just 21 days. It’s too short a time period for the neuropathways to form the habit-friendly patterns in your brain for the new behavior you’re trying to embrace.

The myth of 21 days may have come, according to PsyBlog, from a book about research conducted on how long it took amputees to adjust to the loss of a limb. But that research was published in 1960 and didn’t really examine habits, but rather adaptation to a life-changing event.

Researchers (Lally et al., 2009) wanted to better understand how long it took, on average, for a group of people to form a new habit in their life, such as going for a daily run or eating a piece of fruit every day. The study was published in the European Journal of Social Psychology by Phillippa Lally and colleagues from University College London.

At least 2 months (or about 66 days, on average), according to this study of 96 people. And good news — the researchers did not find that missing one opportunity to perform the new habit behavior did not materially affect the habit formation process. You can safely forget or skip a day and still successfully build that new habit.

Back in 2009, PsyBlog examined the topic for a blog entry that looked at what the research tells us about how long it takes us to form a new habit. Here’s what they had to say:

Although the average was 66 days, there was marked variation in how long habits took to form, anywhere from 18 days up to 254 days in the habits examined in this study. As you’d imagine, drinking a daily glass of water became automatic very quickly but doing 50 sit-ups before breakfast required more dedication (above, dotted lines). The researchers also noted that:

  • Missing a single day did not reduce the chance of forming a habit.
  • A sub-group took much longer than the others to form their habits, perhaps suggesting some people are ‘habit-resistant’.
  • Other types of habits may well take much longer.

So 66 days later, a simple habit might be in place and on automatic pilot. But as the research shows, it could as long as 8 and a half months for more complicated habits to take hold.

Don’t let this dissuade you from trying to retain a new habit. The simple upshot from this research is that habits take time to form — likely 3 times as long as you may have thought. If you’re like most people, give yourself at least 3 months to form a habit, and your new habit should take hold in your life without further effort.