The Myth of 21 Days: How Long Does It Really Take to Build a Habit?
The Myth of 21 Days: How Long Does It Really Take to Build a Habit?
The 21-Day Habit Myth
Have you heard the claim that it takes 21 days to form a new habit? It sounds appealing—just commit to something for three weeks, and it will become second nature. But if you’ve ever tried to build a long-term habit, you probably know it’s not always that simple.
For example, if you decide to eat a piece of fruit each day, does it automatically become second nature after 21 days? Maybe—but for most people, habit formation is much more complex. The idea of a 21-day timeframe is a myth that has been repeated for decades, but research shows that the actual habit-building process varies significantly from person to person.
What Science Says About Habit Formation
A 2009 study published in the European Journal of Social Psychology by Dr. Phillippa Lally and colleagues at University College London challenged the 21-day myth. They found that forming a habit takes an average of 66 days, but it can take anywhere from 18 to 254 days, depending on the behavior, the individual, and their environment.
This means some people may adopt habits quickly, while others require months of repetition. The study also showed that missing a day or two doesn’t necessarily derail the process, but consistency over time is key.
Why “Bad” Habits Are Easy and Healthy Habits Take More Effort
Some habits are effortless to pick up—checking social media, scrolling through emails, or grabbing a snack when bored. These behaviors provide immediate rewards, like entertainment or a dopamine boost, which make them easier to repeat.
On the other hand, healthy habits—like eating more vegetables, exercising, or drinking enough water—often take more effort and don’t always provide instant gratification. This makes them harder to stick with, especially in the beginning.
Think about brushing your teeth. Most of us don’t even think about it—it’s a deeply ingrained habit. But at some point in childhood, we had to be reminded to do it until it became automatic.
Building a Habit That Sticks
Rather than getting discouraged by the myth of a “quick fix,” consider these steps for building lasting habits:
Start small. Instead of a major overhaul, focus on one small habit at a time.
Be consistent. The more frequently you repeat a habit, the faster it becomes automatic.
Track your progress. Seeing improvements, even small ones, can keep you motivated.
Allow for setbacks. Missing a day (or even a few) won’t ruin your habit—it’s about the long-term pattern.
Find your “why.” Habits tied to personal values or goals are more likely to stick.
Long-Term Change Takes Time
Don't be discouraged if you’ve ever struggled to maintain a habit. Many habits take months—not just 21 days—to truly form. And even once a habit is established, life changes (injury, stress, a busy schedule) can cause disruptions. The key is getting back on track rather than expecting perfection.
I’ve personally experienced this with exercise. When I first attempted a 5K, it was tough, and I wasn’t well-prepared, but I did finish. But instead of giving up on running after that, I set a five-year goal to run a marathon. It didn’t happen overnight—it took small steps, from 5Ks to 10Ks, half marathons, and finally, a full marathon in four years, not five. Then, due to an injury unrelated to running, I had to stop running altogether. Restarting an exercise routine in a different way was challenging, but with time, I found a new routine that worked.
This is the reality of habit formation. It’s not about quick fixes—it’s about persistence.
The Bottom Line
Forget the 21-day rule—habit formation is a process that varies for everyone. Some habits take weeks, others take months, and some may need continuous adjustments. The key is patience, consistency, and allowing yourself the time needed to create lasting change.
So, if you’re trying to build a new healthy habit, keep going—it may take longer than 21 days, but it’s possible and normal.
Real World Nutrition Refreshed: I am revitalizing and updating my archive of blogs and re-publishing them. Stay tuned as I review, update, refresh, and re-share these posts to provide you with even more valuable information on nutrition, health, and overall wellness—and keep things timely. A portion of this blog was initially posted on December 15, 2022, and is updated here.
