How long does it take to form a habit? That’s a question many people who are keen on transforming themselves and adopting new habits keep on asking. So what is the answer?

In most self-help and motivational literature you will usually find either the number 21 or 30 days. I wanted to find out where these numbers come from.


I got excited when in one piece of literature I found the mention of an old study that was done by NASA. The study that was described was supposed to test the physiological and psychological effects of weightlessness on humans and the resulting spatial disorientation.

Each of the astronauts had to wear convex goggles which flipped their vision of the world 180 degrees, meaning they saw everything upside down. They were supposed to wear these goggles 24/7.

It was a struggle for all of them at first, however after 26 to 30 days something happened to all of the test subjects. Their vision flipped the right side up! They could now see normally even while wearing the goggles.

This was proof that it takes about one month for your brain to rewire and form a new habit. So that’s where the number 30 comes from.

The study is cited in several self-help books, for example by Jack Canfield or John Assarraf. This most likely influenced other people who were creating habit-formation courses and material to put the number of days at 30. Examples of these include: “30 Days to Healthy Eating” by Annie Howell, or “30 Days of Discipline” by Victor Pride, plus many others.

The problem is that this study probably doesn’t exist. I tried searching for this study all over the internet. If this study is so ground-breaking, as it is cited by many self-help gurus, surely it must be all over. Yet, I couldn’t find it.

My guess is that the story evolved into an urban legend from actual experiments that were conducted in the 1950s, but not by NASA. The experiments involved an Austrian professor, Theodor Erismann, strapping upside-down goggles on one of his students, Ivo Kohler, and then observing what would happen.

They even produced a documentary film on these experiments (shown below):

Supposedly, after 10 days, Kohler managed to adjust to his new reality and everything started to seem normal to him and he started to function normally.

I did find a paper about a study on inversion sponsored by NASA (involving students from Nevada, not astronauts), but it had no mention of anything to do with 30 days.

Most likely somehow, in a game of telephone, the research by Kohler and others got bundled up with the number 30 and NASA and ended up serving as a “source” for the statements on habits of many self-help gurus. Unfortunately none of these gurus actually bothered to check the actual research itself. Instead, they just spread the message that they read from another guru, further and further.

So many citations for a non-existing study. Any real scientist would be proud. 🙂

The number 21 also has an interesting history. The source of this number is this little quote by Maxwell Maltz in his book “Psycho-Cybernetics”:

Invest 30 minutes a day for 21 consecutive days on quiet reflection, working on this with yourself, in solitude.

The book where this quote comes from is the ultimate source of almost all the modern self-help gurus, from Tony Robbins to Zig Ziglar. The author, Maxwell Maltz, was initially a plastic surgeon who noticed one thing: that many of his patients, even after getting a plastic surgery to get rid of their imperfections, were still unhappy.

He surmised that their root source of unhappiness was internal, deep in the mind. So he set out to combat this by trying to change the mindset of his patients through techniques such as visualizations.

After several years, he ended up writing a book where he summarized his observations and described some of his techniques. Many budding self-help gurus started their careers by reading the book.

In the book, Maltz keeps repeating the number 21 for the number of days people should do the exercises he suggests. One of the self-help gurus probably read that and somehow interpreted it to mean that you can form a habit that sticks after 21 days. This then ended up getting repeated by other gurus and that’s how it became “common knowledge” that you can transform a habit in 21 days.

So you see, these commonly repeated numbers are just self-help bro science. This doesn’t mean that the number and techniques behind that number are ineffective. It just means that they are not backed by scientific research.

However, there is one recent study from 2009 that did look into how long it takes to adopt a habit. The results varied between 18 to 254 days, with the average being 66. The conclusion? It takes a long time to get a habit to be automatic, at least 2 months, but usually more.

image 1

5 thoughts on “How Long Does It Take To Form A Habit?”

  1. Hey man. I like that you actually looked into the science of this. I know I’ve used 30-day trials because I heard it all over the place. I can attest from my experience most habits didn’t form automatically after 30 days of trying something new. The ones that did stick took more than 30 days of conscious effort. There’s an interesting trait, though, I’ve noticed about habits that have become automatic. In order for them to become a part of me, I had to consistently experience enough of the benefits of that new habit outweighing the benefits of the old habit or not doing the new one. Somehow replacing that reward. A great example is working out. Eventually, the positive experience after exercise was re-wired into my experience, where that became normal. Then when I wouldn’t work out, I would crave being normal again, otherwise I felt not good! I hope that makes sense. Anyway, love hearing about your journey to Legend!

    1. Hey Colin!

      Thanks for taking the time and writing out such a comprehensive comment! 🙂

      Yeah, it’s an interesting thing about how the brain works with habits. For me working out has become a must do. If I don’t do it, then I feel like shit. If I skip some of my workout sessions, I start feeling like shit and only get my energy back after a hard session at the gym. Partially, this might have to do with dopamine. When working out becomes a habit and you enjoy doing it, then the brain releases dopamine, which makes you feel good. If you skip out on the sessions, then the dopamine doesn’t get released and you feel bad. Here is an interesting article on the subject:

      1. Fasho mate. I can totally relate. And the cool part is, that it wasn’t always that way. I used to hate working out and never did it. Then over the course of a year or so it was transformed, almost by accident. The next part of this habit stuff that I find interesting is how to apply it to things or other routines that don’t have such a direct a physiological link to happy chemicals, and how to somehow train the mind to give rewards for behaviors that we want to do, but just suck to do. If that makes sense

        1. Sucking at things is always the first step. There are four levels of competence: unconscious incompetence, conscious incompetence, conscious competence, unconscious competence. Usually when you are sucking at something and you know it, you find yourself at the second level conscious incompetence. You have to surpass this level through the use of your willpower. Unfortunately, this level is also the most painful and most people will give up, so you need to use up a lot of your mental will to overcome it. Some things that help include creating a good environment around you, having friends push you through, always having a visualization of the benefits of becoming competent at that activity in front of you to push you…etc. After that stage, things will start becoming more and more automatic.

          1. Well said, I think the empowering environment can’t be overstated. It’s very helpful when you have encouraging people, and mentors to help along the way. Some might say it’s a virtually essential component to make changes.

Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.