We often seek guidelines that clarify the duration and effort required to achieve our tasks, believing that our efforts will be fruitful in the long run. The 21/90 rule fits all these requirements when it comes to self-improvement. However, how accurate is this rule?

This article explores the 21/90 rule and assesses its validity as a framework for habit formation and lifestyle transformation.

What is the 21/90 Rule?

The 21/90 rule is a theory that suggests you need 21 days to turn any behavior into a habit and 90 days to solidify that habit into a lifestyle. Many have used and tested this theory to achieve positive change.

The Theory Origin

The concept of the 21/90 rule was first introduced by Dr. Maxwell Maltz, a plastic surgeon, in his 1960 self-help book Psycho-Cybernetics.

Is the 21/90 Rule Accurate?

The 21/90 rule is a simple method for acquiring habits and changing lifestyles. Its accuracy depends on two critical questions: Is forming a habit in 21 days possible? And can permanent lifestyle changes occur in 90 days?

1. Is It Possible to Form a Habit in 21 Days?

In a 2009 study led by medical researcher Phillippa Lally, it was found that it takes approximately 66 days to establish a new habit—45 days longer than the 21/90 rule suggests. This indicates that forming a new habit within just 21 days is unlikely.

2. Can Permanent Lifestyle Changes Be Made in 90 Days?

The rule also states that it takes 90 days to make permanent lifestyle changes. However, these lifestyle changes are merely changes in habits.

Forming a new habit takes an average of 66 days, so changing a lifestyle within 90 days is possible. However, the 21/90 rule asserts that these lifestyle changes are permanent, and this is its issue.

Life is inherently unpredictable; factors such as job demands, personal loss, or stress can significantly impact your habits. As circumstances evolve, it is common for previously established habits to regress, potentially leading back to undesired behaviors.

Ultimately, habits are not eternal. Whether they last for 90 days, a year, or even five years, maintaining a positive lifestyle—especially one that is challenging—requires continuous effort.

Applying the 21/90 Rule for Life Changes

While the 21/90 rule may be inaccurate, it still catalyzes positive change.

The psychological aspect of committing to a task for 21 days may feel less daunting than pledging to maintain it for 66 days, bolstering your initial willpower and motivation.

However, it is important to recognize that willpower is not always dependable; more effective strategies exist for cultivating lasting habits. While you may not fully adopt a new habit within the initial 21 days, repeated practice will likely make the behavior easier over time.

Conclusion

The 21/90 rule claims that a new habit can be formed in 21 days and that lifestyle changes can be permanently established in 90 days.

However, research indicates that forming a new habit takes an average of 66 days—45 days longer than what this theory suggests. Life is unpredictable, and permanent lifestyle changes cannot be guaranteed, and quality may vary.

Although the 21/90 rule may be flawed, it can still be used to initiate positive change. Remember, there are more effective tools for building habits.