Michelle from Hialeah, Florida contacted me via my website (HypnosisForHumans.com). Michelle wants to exercise daily and is wondering how long it will take to develop that habit.

If you've done any research on changing a habit, you've probably heard the phrase, "It takes 21 days to change a habit." You may have even shared this piece of knowledge with a friend or family member.

Well, stop whatcha doin', 'cause I'm about to ruin the image and the style that you're used to.

What you may have learned is a lie.

Here's what you need to know…

Maxwell Maltz, a plastic surgeon circa 1950s, began noticing a pattern with his patients. After an operation, such as a nose job, Maltz discovered that it took approximately 21 days for the patient to get used to seeing their new face. Maltz noticed the same thing when a patient had an arm or leg amputated; the patient would sense a phantom limb for about 21 days before adjusting to the new situation.

Maltz's exact quote was, "These, and many other commonly observed phenomena tend to show that it requires a minimum of about 21 days for an old mental image to dissolve and a new one to jell."

Maltz generalized this 21-day phenomenon to all behavior changes and published his theory in his 1960 book, Psycho-Cybernetics, which sold more than 30 million copies.

There are a couple of glaring issues with this pseudo-fact…

1. Maltz said, "a minimum of about 21 days".

2. There was no study; it was only an observation that Maltz made with his clients.

So, What Should You Expect?

Phillippa Lally is a health psychology researcher at University College London. In a study published in the European Journal of Social Psychology, Lally and her research team decided to determine how long it takes to form a habit.

The study tracked the habits of 96 humans over 12 weeks. Each human chose one new habit for the 12 weeks and reported each day whether they did the behavior and how automatic the behavior felt.

For example, some chose habits such as drinking a bottle of water with lunch while others chose more difficult habits like running for 15 minutes before dinner. At the end of the 12 weeks, researchers analyzed the data to determine how long it took each human to go from starting a new behavior to automatically doing it.

The findings… It takes an average of 66 days for a new behavior (habit) to become automatic.

Lally's study found that it takes anywhere from 18 to 254 days for people to form a new habit depending on what you're attempting to change and how much leverage you have on yourself. In other words, depending on the amount of (emotional) pain you link to what you no longer want to do and the amount of (emotional) pleasure you link to the new behavior, your timeline may vary.

Bottom line… It could take a long time to change a habit. So, give yourself a realistic timeline instead of the 21-day myth.