Forming Healthy Habits Takes Patience and Time

WASHINGTON — Did you set any health-related goals for the new year? If so, are you still working toward them? We’re one month into 2025, and the excitement of trying a new habit may have worn off. While a popular claim states it takes 21 days to form a new habit, a new review finds it takes longer.

Let’s take a look at the new review and the varying length of time it may take for different habits to form. We’ll also explain the mechanisms behind habit-forming and the steps you can take to make new behaviors automatic.

How to Form a Habit

In the new review published in the Healthcare Journal in December 2024, researchers at the University of South Australia analyze several studies on different health habits to identify how long it takes to form them and what happens during the process. 

First, they explain habit formation based on previous research, which suggests it occurs in four stages:

1. The decision to take action.
2. Acting on the new behavior for the first time.
3. Repeating the behavior consistently within the same context.
4. Reaching automaticity.

Other research includes the importance of interrupting a current unhealthy habit and replacing it with a new one. 

Repetition within the same context over a long period leads to the final step of habit formation: automaticity. To recognize if a behavior has reached automaticity, it must be performed with a “lack of awareness, efficiently, uncontrollably, or unintentionally.” 

Overcoming the friction or resistance you face when trying to stop or adopt a new behavior can be challenging. The best chance of long-term success is to find a way to make the new behavior “easy and automatic.” One suggestion is to add your new habit to a current, healthy habit to create a routine.

The 21-day theory came from a 2002 book called Psycho-Cybernetics by Maxwell Maltz but did not have ample evidence. The new review attempts to find a magical number.

Time to Form a Habit: A Systematic Review and Meta-Analysis of Health Behaviour Habit Formation and Its Determinants

The new review and analysis examines 20 studies.

Participants

There were 2601 total participants across the studies. Each study included 20 to 537 individuals. Participants were an average of 21.5 to 73.5 years old. One study only included women and the rest were a mix of men and women.

Participants included university students, hospital patients, older adults, people with overweight or obesity and members of the general public.

The studies ranged from three weeks to two years. Four studies measured the time it took to reach automaticity.

Tracking Health Behaviors

The included studies tracked seven different health behaviors:

• Physical activity.
• Drinking water.
• Vitamin consumption.
• Flossing.
• Healthy eating.
• Microwaving a dishcloth (to reduce foodborne disease risk).
• Reducing sedentary behavior.

Studies used different ways of tracking these behaviors, including:

• Wearable technology.
• Mobile apps.
• Text, email and video messages.
• In-person or virtual counseling and workshops.
• Informational programs.
• Planning activities.
• Self-monitoring and reporting.

Time to Reach Per Behavior

Here is what they found for how long it took to form some of the habits, per each study that included the timeline:

• Healthy eating: Four to 355 days, a median of 59 days. Only 23% achieved habit formation status.
• Healthy eating, water consumption, and exercise habits: Eighteen to 254 days, with an average of 66 days to reach automaticity.
• Healthy eating and self-weighing: An average of 91 days.
• Daily stretching: An average of 106 days for morning stretching and 154 days for evening stretching.

Determinants

Here is what helped determine habit-forming in each stage.

1. Deciding to take action:
   • Drinking water was more successful than exercise and healthy eating habits.
   • Flossing was strongly influenced by the decision to act.
   • Stronger habits emerge when the individual chooses the goal. 
2. Repeating the behavior:
   • Daily stretching was more effective in the morning than in the evening.
   • There was no difference in the time of day for drinking water.
   • Participants who performed a new behavior in a consistent context emerged with stronger habits.
   • Repeating behaviors early in the process increases automaticity more than repeating them later on.
   • Self-monitoring increased the likelihood of repetition.
3. Automaticity: The following aspects influenced the chance of reaching automaticity.
   • Enjoyment of the new behavior.
   • Regulating the behavior .
   • Adding a preparatory habit, for example choosing exercise clothes, increased the physical activity habit.
   • The time it took to reach automaticity varied per habit — multiple studies found it took more than one month.

Results: Average Time and Determinants

The review concludes with the average time across all studies that it takes to form a habit:

• The median range is 59 to 66 days (two to three months).
• The average range is 106 to 154 days (three to five months).
• Health habits can require two to five months to reach automaticity.

The most common determinants that influenced habit success:

• Frequency and timing.
• Type of habit and stable context.
• Intention to perform. 
• Enjoyment.
• Specific plans to perform.
• Daily routines or habit stacking.

Limitations and Implications

The primary limitation is that the review covers only a small number of studies and lacks sufficient evidence for each health behavior. The results cover a wide range of periods.

However, each one shows habit formation takes longer than the previously assumed 21 days. Researchers note the implications of this finding for individuals and health professionals.

• Don’t give up if your new behavior doesn’t feel automatic and easy after only three weeks; it may take several months.
• Short-term three-week challenges are unrealistic.
• Encourage patients and the public to work toward long-term lifestyle changes rather than instant, quick fixes.

New Habits Take Time

Trying out a new habit? The latest research finds that repeating it consistently, in the same context, at the same time of day, and continuing for months is the best way to make long-term change. While it doesn’t sound fun, finding a way to enjoy the behavior can significantly boost your success at automaticity. 

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