We often set ambitious goals, such as going to the gym, adopting healthier eating habits, or reducing our social media use. However, despite our best intentions, staying committed can often feel like an uphill battle.
Author
- Eike Buabang
Research Fellow, Trinity College Institute of Neuroscience (TCIN), Trinity College Dublin
A review of evidence published in 2024 highlights why. While understanding the benefits of behaviour change and believing in its value are important, these play only minor roles. The strongest determinant of our ability to shift how we act everyday is our habits.
As the 19th and 20th-century philosopher William James put it, we are essentially "bundles of habits". He believed that these habits could hold people back from achieving their full potential. If he were around today, he would probably be concerned at the way some people mindlessly check their phones every five minutes.
In a recent academic review , my colleagues and I at Trinity College Dublin illustrated that habits are governed by a delicate balance between two distinct brain systems. One system drives automatic responses to familiar cues in the environment, while the other enables the control of behaviour directed towards goals.
This interplay helps explain why we might mindlessly scroll through social media when bored, yet still retain the ability to deliberately put our phones away to focus on work. We reviewed decades of research from laboratory studies and real world settings for the study. Here, we share five practical strategies to help you build positive habits and break negative ones.
1. Forget the 21-day myth
Forget the 21-day rule - there is no magic number. This rule refers to a popular perception that it takes 21 days to form a new habit. Habit formation is different for every person.
In one study , habit formation such as having a piece of fruit with lunch was estimated to take 66 days on average, but it varied widely between individuals, from 18 days to 254 days.
It also depends on the specific habit itself. A study demonstrated this using a subset of AI called machine learning. The study analysed more than 12 million gym visits and 40 million instances of hospital handwashing to understand how habits form.
The research found that forming a gym habit typically takes months, while hospital staff can develop a handwashing habit in just weeks. No matter how long it takes, the key is sticking with it, even if you miss a day here and there.
2. Make rewards your ally
Your brain learns to repeat behaviour that is rewarding. One study examining people's intake of water throughout the day found that it was more of a habit for people who perceived it as more rewarding.
The habit loop can also be reinforced through external rewards, such as treating yourself to something enjoyable after completing a workout.
Rewards are also important for breaking habits. If scrolling through social media becomes a way to unwind, try replacing it with an alternative activity that provides a similar sense of relaxation and enjoyment.
By substituting a positive behaviour, you not only avoid feeling deprived but also create a competing response to the old habit, making it easier to break the cycle.
3. Stack your habits
The brain has a natural tendency to combine different actions and respond to contextual cues - the kind that help people understand their surroundings. A strategy called habit stacking takes advantage of this by linking a desired behaviour to something you already do.
For example, research on flossing found that people who flossed immediately after brushing their teeth were more likely to establish a lasting habit. The existing cue - brushing your teeth - serves as a reminder, making the new habit - flossing - feel like a natural part of your routine.
So, if you want to start meditating, pair it with your morning coffee. Sip your coffee, then meditate for five minutes. Over time, the two types of behaviour become intertwined, making it easier to stick with your goals.
4. Watch out for stress
When life gets overwhelming, many of us find ourselves falling back into old habits, even ones we thought we had moved past. Acute and chronic stress can shift the balance away from controlled goal directed behaviour towards the automatic response system in the brain.
A functional magnetic resonance imaging (fMRI) study revealed that prolonged stress in humans leads to an over-reliance on the brain's circuits that drive habits, while suppressing the prefrontal cortex, which governs deliberate decision making.
The good news? These effects are reversible. After a six week stress-free period, participants returned to goal directed behaviour, and their brain activity normalised.
5. Plan for weak moments
We like to set new ambitious goals when we feel motivated. Motivational changes are often initiated based around time, such as the start of a new year, a phenomenon known as the "fresh start effect" . But it is important to be strategic and prepare for situations when motivation is low and we still want to work towards our goals.
A powerful strategy for overcoming these weak moments is to plan ahead for specific situations by saying, "If I find myself reaching for a snack when I'm stressed, then I will take a five-minute walk instead." This strategy is generally referred to as "if-then" plans.
This approach helps to preemptively trigger a healthier response in those moments when bad habits might otherwise take over.
So, while it might seem difficult, if you're looking to rid yourself of a bad habit or replace it with a good one, our research suggests it's possible to change your behaviour using strategies based on scientific evidence.
Eike Buabang receives funding from the Government of Ireland Postdoctoral Fellowship Programme.
