In their systematic review, researchers from the University of South Australia found that new habits can begin forming within 2 months but may take up to 335 days to fully establish. “While common wisdom suggests that it takes just 21 days to form such habits, these claims are not evidence-based,” said lead author Dr Ben Singh.
This finding is important in shaping public health interventions and encouraging individuals to persist in their habit-forming efforts beyond the mythical 3-week threshold. If people expect quick results, they may become discouraged and abandon their goals too soon. Understanding the realistic timeline of habit formation can help people remain motivated and committed to long-term health changes.
Why do some habits take longer to form than others?
The time it takes to form a habit varies significantly depending on the individual and the behaviour being adopted. The study, which analysed data from over 2,600 participants, found that some people formed habits in as little as 4 days, while others took 1 year.
Dr Singh explains: “In our research, we’ve found that habit formation starts within around 2 months, but there is significant variability, with formation times ranging from four days to nearly a year.”
Several factors influence how quickly a habit becomes automatic:
Frequency of practice: The more often a behaviour is repeated, the stronger the habit becomes. For example, brushing teeth is easier to establish as a habit than a weekly exercise routine.
Timing of the habit: Research suggests that morning routines are more likely to stick. If a person integrates a habit into their morning, they are more likely to maintain it.
Enjoyment and personal choice: People who find a habit enjoyable or have chosen it themselves are more likely to sustain it over time.
Context and consistency: Habits performed in a stable environment, such as drinking a glass of water after brushing teeth, are easier to develop than those requiring variable conditions.
Strategies to make habit formation easier
Despite the lengthy and variable timeline for habit formation, there are strategies that can help solidify new behaviours more efficiently. Planning and integrating habits into daily routines can significantly boost success rates.
“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,” suggested Dr Singh.
Some effective strategies include:
Attaching new habits to existing ones: If you want to start taking vitamins daily, do it right after brushing your teeth so it becomes a natural extension of an existing habit.
Preparing in advance: Laying out gym clothes the night before can increase the likelihood of following through with morning workouts.
Tracking progress: Keeping a habit tracker or journal can help reinforce consistency and provide motivation.
Choosing habits that align with personal preferences: People are more likely to stick to habits they enjoy, such as dancing instead of running for exercise.
Expect a marathon, not a sprint
The widely believed notion that habits form in 21 days is not supported by scientific evidence. Instead, research indicates that it takes at least 2 months, and sometimes much longer, to turn new behaviours into lasting habits. This understanding is critical for individuals looking to adopt healthier lifestyles, as well as for public health campaigns aimed at encouraging long-term behaviour change.
Rather than becoming discouraged at the three-week mark, individuals should expect habit formation to be a gradual process. As Dr Singh advises: “It’s important for people who are hoping to make healthier habits not to give up at that mythical three-week mark.”
