People Can Change. The Trick Is to Stop Waiting to Feel Like a Different Person.

“People don’t change” is easy to say when someone disappoints us—or when we catch ourselves repeating the same old pattern. But people do change. The harder question is how to make that change survive ordinary life.

Originally published on September 3, 2024, this article has been substantially rewritten with current research on personality change, habit formation and the surprisingly important role of context in making new behaviours stick.

There is a particular kind of frustration that comes from deciding, with complete sincerity, that you are going to change—and then watching yourself do the old thing again.

You promise you will exercise before work. Three mornings later, the alarm rings and you negotiate yourself back under the duvet. You decide you will stop checking your phone every six minutes, then find it in your hand without remembering picking it up. You tell yourself you are going to become calmer, more organised, less reactive, better with money, kinder to your knees.

For a while, the new version of you seems entirely plausible.

Then Tuesday happens.

This is why I think “Can people change?” is slightly the wrong question. The evidence suggests that people are capable of changing in behaviour and even in aspects of personality. A 2026 meta-analysis pooling 229 longitudinal studies and more than 230,000 people found meaningful individual differences in personality change throughout the lifespan. We are not fixed at 25 and condemned to spend the next 60 years reenacting the same character.

The more useful question is: What allows an intended change to survive ordinary life?

Wanting to Change and Changing Are Different Jobs

Motivation matters because it gets us moving; it is simply not especially reliable as the only thing keeping us moving. Most of us know this intuitively. The first week of a new routine can feel almost effortless because the decision itself is exciting: the running shoes are clean, the notebook has no crossed-out pages and the kitchen contains suspicious quantities of vegetables. Six weeks later, none of it is new anymore.

This is where habits become interesting. In psychology, a habit is not simply something you do often. Habitual behaviour becomes increasingly tied to cues in the surrounding context, so the situation itself begins helping to prompt the response. With repetition in relatively stable circumstances, a behaviour can become more automatic and less dependent on making a fresh decision every time.

That is the difference between “I want to exercise more” and “I walk for ten minutes after lunch.” The first is an intention. The second has the beginnings of a behavioural system.

Stop Trying to Become a Different Person by Monday

The original version of this article told readers to “start small,” which is perfectly sensible advice but not especially useful until we explain why.

A small behaviour is easier to repeat.

And repetition is doing much of the work.

One of the classic real-world habit studies followed 96 people who chose a new eating, drinking or activity behaviour and attempted to repeat it every day in the same context—for example, doing something after breakfast. As repetitions accumulated, the behaviour tended to become more automatic.

This is why I would rather begin with:

After I pour my morning coffee, I will take my medication.

than:

I am going to become someone who takes much better care of himself.

The second is admirable. The first tells Tuesday morning what to do.

And No, It Does Not Take 21 Days

Few numbers in self-improvement have enjoyed a better career than 21 days.

Unfortunately, human behaviour did not agree to the schedule.

In the well-known habit-formation study above, the estimated time to reach near-maximum automaticity ranged from 18 to 254 days among participants whose data could be modelled successfully. The often-repeated figure of about 66 days was a median estimate, not a deadline.

Newer evidence makes the variation look even larger. A 2024 systematic review examined 20 studies involving 2,601 participants, although only four directly reported how long habit formation took. Across those studies, median estimates were around two months, some mean estimates stretched beyond three or even five months, and individual estimates ranged from 4 to 335 days. The evidence base is still relatively modest, but one conclusion is difficult to miss: there is no universal countdown after which a behaviour suddenly becomes a habit.

So if you have been doing something for three weeks and it still requires effort, nothing has gone wrong.

Your brain has not missed a deadline.

The Part We Underestimate: Where and When

I used to think changing a habit was primarily a contest between the sensible part of you and the lazy part.

The research makes the environment look much more important than that.

In a six-week study of university students building study habits, participants who performed the behaviour in a more stable context developed greater automaticity and were more likely to meet their repetition goals than those whose context varied.

Earlier work provides an even more intuitive example. Researchers studying students who transferred universities found that established behaviours such as exercising, reading newspapers and watching television were disrupted when the contexts that normally cued them changed. When parts of the old context survived the move, the habits were more likely to survive with them.

That explains a peculiar experience many of us have had: you go on holiday and suddenly stop wanting the 3 p.m. snack you “couldn’t resist” at work. You move house and, for a few weeks, your evening seems to have different rules. You change jobs and an old routine either disappears effortlessly or collapses completely.

The person did not change overnight.

The cues did.

What I Wish I’d Known Earlier: sometimes the easier way to change your behaviour is not to demand more discipline from yourself. It is to stop placing the old behaviour in exactly the same situation and expecting a new result.

Make the Good Choice Easier to Encounter

This gives us a much more practical way to think about change.

If you want to read more, leaving the book on the bedside table may matter more than promising yourself that you will become “a reader.”

If you want to walk after lunch, decide where the shoes live and what counts as lunch being finished.

If you want to stop taking your phone to bed, charging it across the room changes the situation in which the unwanted behaviour normally occurs.

None of these tricks guarantees anything. They simply reduce the number of moments in which your new behaviour has to defeat your old one in open combat.

And when a predictable obstacle exists, a specific plan can help. Psychologists call these implementation intentions: plans that connect a situation to a response—essentially, when this happens, I will do this. The useful part is that you have made the decision before the troublesome moment arrives..

So instead of:

I won’t snack tonight.

you might decide:

When I finish dinner, I’ll make tea and leave the kitchen.

Much less inspirational.

Much more useful at 9:17 p.m.

Missing a Day Is Not the Same as Failing

This may be the most merciful finding in the habit literature.

In the original Lally study, missing a single opportunity to perform the behaviour did not materially derail the habit-formation process.

That is important because many habit systems accidentally teach perfectionism.

Miss Monday’s walk and somehow Tuesday becomes evidence that the whole programme has collapsed. Eat one unplanned meal and the diet is “ruined.” Forget to meditate and the streak counter returns to zero, as though the previous 43 days have been erased from neurological history.

Real behaviour change is messier.

The goal is not to construct an unbroken museum exhibit of good decisions. It is to make one behaviour increasingly normal.

A missed repetition is a missed repetition; return at the next sensible opportunity.

Your Old Habits May Not Disappear

There is another uncomfortable part of the science: learning a new routine does not necessarily erase the old one.

Habit research suggests that established responses can remain linked to the contexts in which they were learned. Changing the environment can weaken their grip, but old patterns can re-emerge when familiar cues return.

Anyone who has visited their childhood home and found themselves behaving strangely like their 17-year-old self may not require a laboratory demonstration of this.

It also explains why deliberate change can feel unfairly difficult. You are not always starting on an empty page. Sometimes you are trying to write a new routine over one that has been rehearsed for years.

That does not mean the old behaviour will win.

It means you should stop interpreting its reappearance as proof that you never changed.

Can You Change Your Personality Too?

This is where the answer becomes more cautious.

Personality traits are relatively enduring patterns, but relatively enduring does not mean immutable. Longitudinal research shows that personality continues to change across the lifespan, and intervention studies have reported measurable changes in traits such as emotional stability and extraversion. A 2017 systematic review of 207 intervention studies found changes in measured personality traits over an average period of about 24 weeks.

A later randomized digital intervention involving more than 1,500 people also found changes in the directions participants were trying to move, with some changes noticed by friends or family as well as by participants themselves.

But this field deserves some humility. A 2025 set of randomized studies found that people assigned to personality-change interventions improved, but control participants changed similarly, raising questions about expectancy, selection and how much of the measured improvement should be credited to the intervention itself.

In other words, the evidence does not support either extreme.

You are not permanently fixed.

Nor can you order a new personality like a kitchen renovation.

I Would Start With Behaviour, Not Identity

This is why, if there is something about myself I want to change, I would begin one level below the grand declaration.

Not: I need to become disciplined.
Try: What would a more disciplined person do at 7:30 tomorrow morning?

Not: I need to be healthier.
Try: What is one behaviour I can repeat after something I already do?

Not: I have to become less chaotic.
But: Where do the keys go when I walk through the door?

Identity can follow evidence. Every repetition gives you another small piece of evidence about the sort of behaviour you are capable of sustaining. There is no need to announce the transformation before you have lived any of it.

Some Changes Need More Than a Habit Trick

There are limits to this framework. Addiction, eating disorders, compulsive behaviours, severe depression and other mental-health or medical problems should not be reduced to “bad habits,” nor should difficulty changing them be interpreted as a lack of discipline.

Habits can be part of the picture without being the whole picture. When a behaviour is causing serious harm, feels uncontrollable or is bound up with a health condition, professional support may be considerably more appropriate than another productivity system.

For ordinary behavioural change, though, I would make the ambition surprisingly modest: choose something specific, attach it to a context that occurs reliably, make the behaviour easy enough to repeat and expect the process to take longer than the internet promised.

Then keep returning.