Forming healthy habits takes much longer than 21 days

If you’re already struggling with your 2025 resolutions, here’s some reassuring news: it’s not you, it’s science. New research from the University of South Australia (UniSA) suggests that forming a healthy habit takes longer than most people expect.

Debunking the 21-day habit myth

For years, a popular belief suggested that it only takes 21 days to form a habit. This idea has been widely circulated in self-help books and social media.

However, UniSA researchers have now challenged this notion with a systematic review that is the first of its kind. The study shows that while new habits can begin forming within two months (typically between 59 and 66 days), they can take up to 335 days to become fully established.

Dr. Ben Singh, a researcher at UniSA, explained that adopting healthy habits is a long and often difficult process. He stresses that the idea of forming a habit in just three weeks is not supported by scientific evidence.

“At the beginning of the year, many of us are setting goals and making plans for the months ahead – things like being more active, cutting back on sugar, or making healthier food choices – but while common wisdom suggests that it takes just 21 days to form such habits, these claims are not evidence-based,” noted Dr. Singh.

He emphasizes that habit formation is highly variable and can take anywhere from four days to nearly a year, depending on several factors.

Why forming healthy habits matters

Chronic diseases remain one of the biggest health challenges in the world. Conditions such as type 2 diabetes, heart disease, lung diseases, and stroke contribute to a significant portion of the country’s disease burden.

Fortunately, many of these illnesses can be prevented by making lifestyle changes, such as improving diet, increasing physical activity, and quitting smoking.

Understanding how long it takes to form a new habit is crucial for designing effective health interventions.

If people realize that habit formation is a long-term process rather than a quick fix, they may be less likely to abandon their efforts prematurely. This research can also help guide public health campaigns and individual strategies aimed at encouraging long-term behavior change.

Factors influencing habit formation

The UniSA study, which examined over 2,600 participants, found that certain factors influence how successfully a new habit is formed. One of the most important elements is consistency. The more frequently a person engages in a new behavior, the more likely it is to become a habit.

Timing also plays a role. Dr. Singh notes that habits incorporated into morning routines are more likely to stick. The reason behind this is that morning routines tend to be more stable and predictable compared to other times of the day.

If a person commits to an activity early in the day, they are less likely to be derailed by unexpected events or fatigue.

Enjoyment is another major factor. People are more likely to sustain a habit if they find it pleasurable or rewarding. For example, someone who enjoys swimming may find it easier to maintain a regular exercise habit than someone who forces themselves to run despite disliking it.

“Planning and intending to complete a new behaviour can also help solidify a new habit, so make sure you continue to make time to include your new healthy habits into your everyday activities,” said Dr. Singh.

Challenges of forming new habits

Many people give up on their resolutions because they expect immediate results. When they don’t see quick progress, they become discouraged and revert to old habits. This research highlights the importance of patience and persistence in habit formation.

Instead of focusing on short-term changes, individuals should view habit-building as a long-term investment in their health and well-being. If a habit doesn’t feel automatic after a few weeks, that doesn’t mean it’s a failure. It simply means that more time and repetition are needed.

It is also essential to be flexible and adaptable. If one approach doesn’t work, trying a different strategy can help.

For example, if exercising in the morning feels unsustainable, shifting workouts to lunchtime or evening may be a better fit. The key is to find routines that are both enjoyable and practical.

Implications for public health initiatives

While more research is needed, these findings have significant implications for public health initiatives. Governments, healthcare providers, and wellness programs can use this knowledge to design interventions that promote long-term habit formation.

Instead of promising quick results, they can emphasize the importance of gradual change and sustained effort.

Personalized programs that take individual differences into account can also be more effective. Since habit formation varies from person to person, interventions should be flexible enough to accommodate different lifestyles and preferences.

By providing support and realistic timelines, these programs can help more people successfully adopt and maintain healthier behaviors.

Staying committed to your goals

If you’re still working on your New Year’s resolutions, remember that forming a new habit takes time. Don’t be discouraged if you don’t see immediate results. Focus on consistency, enjoyment, and planning to increase your chances of success.

Dr. Singh’s research serves as a reminder that habit-building is not about quick fixes but about long-term commitment. Whether you’re trying to eat healthier, exercise more, or break an unhealthy habit, persistence is key.

The journey to better health is not a sprint – it’s a marathon. Stay the course, and over time, your new habits will become second nature.

The study is published in the journal Healthcare.

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