Short answer: To build a habit when you’re exhausted, design it for your tiredest day, not your best one. Shrink the first step until it takes under two minutes, and tie it to something you already do every day. Then write a smaller bad-day version in advance, so a rough evening still counts.
Most habit advice is written by people with spare energy, for people with spare energy. Get up an hour earlier. Prep on Sunday. Stay consistent.
None of it’s wrong. It assumes somebody who isn’t already running on fumes by eight in the evening.
If that somebody isn’t you, the problem isn’t your character. It’s the size of the plan.
Why is it so hard to build a habit when you’re tired?
Because most plans lean on the two things exhaustion takes away first.
BJ Fogg’s behaviour model puts it plainly: behaviour happens when motivation, ability and a prompt come together at the same time. When you’re worn out, motivation drops and everything costs more, so ability drops too. You want it less at nine at night, and it’s harder to do.
That leaves two levers you can pull without waiting to feel better. Make the thing easier, and make the prompt reliable. Neither needs willpower, but both need a clear look at what a bad Tuesday looks like.
How small should a new habit be when you have no energy?
Smaller than feels respectable.
In GROWTH by DESIGN this is called the Minimum Viable Start. Write down the full version of what you want. Halve it. Halve that. Halve it again.
Run three times a week becomes one run a week. That becomes a walk round the block, then putting your trainers on and standing by the door. That last rung is the plan.
Then check it with the Shrink Test. Five questions, each answered yes or no, not roughly:
- Could I do this on my worst day of the last month?
- Could I do it in under two minutes?
- Could I do it without any equipment I don’t already own?
- Could I do it without anybody else’s cooperation?
- Would I be slightly embarrassed to describe it as my plan?
Five yeses and the step is the right size. Any no tells you what to shrink next.
It’ll feel pointless. That’s fine. The first step isn’t there to achieve anything much.
Its job is to prove that the change can be started at your size, on your worst day. Once starting is solved, repeating is a much smaller problem.
And you’ll often do more than the step. Trainers on becomes a twenty-minute walk, because getting going was most of the cost. Enjoy that when it happens, and don’t make it the new requirement.
The moment the twenty minutes becomes the target, you’ve rebuilt the big version, and it’ll break the first time you’re shattered.
What should I attach a new habit to?
Something that already happens, and that you notice happening.
There’s good evidence behind this one. Peter Gollwitzer and Paschal Sheeran pooled 94 independent tests of ‘if-then’ plans, where you decide in advance when, where and how you’ll act. They found a medium-to-large positive effect on people reaching their goals.
The detail that matters when you’re tired: anchor the plan to an event, not a time. ‘At seven o’clock’ arrives while you’re doing something else and doesn’t announce itself. ‘When I put the kettle on’ does.
Kettle on, car door shut, teeth brushed, last email sent, key in the door. You have dozens of these, and they happen whether you feel like it or not.
Write it as one sentence: ‘When I put the kettle on after work, I fill my water bottle.’ Then put it where the event happens. On the kettle, by the keys, in the car. Your tired self won’t go looking for a plan in a notes app.
Repetition in the same setting is also how the habit gets easier over time. In 2012 Benjamin Gardner, Phillippa Lally and Jane Wardle wrote a paper for GPs on this. It sums up the advice as repeating a chosen behaviour in the same context until it becomes automatic.
Same cue, same place, same small action. The setting does a lot of the work that effort gets the credit for.
What is a bad-day version, and why write it in advance?
It’s the same habit shrunk to its floor, decided while you’re thinking clearly.
Most plans have one setting: on or off. So the first rough evening produces a zero, and a couple of zeros start to sound like a story about you. The bad-day version stops that happening, because it’s a smaller version of the change, not a lesser version of you.
Write three sizes, and treat all three as done:
- Standard: when I’ve put the last plate away, I do ten minutes of stretching.
- Bad day: when it’s been a bad day, I stretch one thing, lying on the floor.
- Crisis: when everything is on fire, I put the mat by the sofa where I’ll see it.
The crisis line looks absurd on paper. It’s there so that coming back is easier than carrying on, because after a bad week you’ll be coming back from a worse position.
The bad-day version. If today is one of those days, do the smallest version you can name. Fill the water bottle. Open the document. Put the trainers by the door. That’s the plan for today, and it counts as done.
How can I make it easier without trying harder?
Change the room, not your resolve.
Every habit has a friction cost, and when you’re exhausted you notice every extra step. So work in two directions.
Take steps away from what you want more of. The guitar lives on a stand, not in its case. The trainers go by the door, not upstairs, and the form is already open in a tab.
Add steps to what you want less of: the phone charges in another room, so scrolling in bed means getting up.
Do one of these, not all of them. Pick the one that makes the bad-day version easiest, because that’s the part that has to survive.
What if I miss a day?
You will, and it matters less than it feels.
In the study behind that paper for GPs, missing the occasional day didn’t seriously set people back. Progress picked up again after a single miss.
So the rule in GROWTH by DESIGN is simple. Miss once and it’s a day. Miss twice in a row and it’s the emergency, because two is where a gap starts to become a state.
After one miss, the next go is compulsory, and it’s the crisis version. Don’t do a double session tomorrow to make up for it. There’s nothing to pay back.
When is tiredness a reason to see someone?
Some exhaustion isn’t a habit problem, and no plan will fix it.
The NHS advises seeing a GP if you’ve been feeling tired for a few weeks and aren’t sure why. The same goes if tiredness is affecting your daily life. That’s worth doing before you blame yourself for a habit that won’t stick.
If you’re struggling to cope, the Emergency Kit is free and asks for nothing. In the UK you can call NHS 111 for urgent help, or Samaritans on 116 123, free, any time. Numbers checked September 2026.
Frequently asked questions
What is the easiest habit to start when you are tired?
The one you can do in under two minutes, without equipment, straight after something you already do every day. Filling a water bottle when the kettle goes on is a good example. The habit matters less than its size and its anchor.
How long should a new habit take each day when you have no energy?
Two minutes or less at the start. Let the standard version grow on its own once you’ve been doing more than the minimum, without effort, for a few weeks. Keep the bad-day version the same size for good.
Does a two-minute habit make any difference?
On its own, not much. Its job is to make the habit startable on your worst day. Repeated in the same setting, small actions become automatic over time, and on better days you’ll often do more than the minimum.
Should I build habits in the morning or the evening if I’m exhausted?
Whichever has the more reliable anchor. If your mornings are predictable and your evenings aren’t, use the morning. Tie the habit to an event you notice, like the kettle or the school run, not a clock time.
Read next: How long does it take to form a habit? What the research found and How to stop starting over every Monday.
Want this on paper? The free One-Page Change Plan puts your change on one printable sheet: nine steps, in order, sized for a bad day. It comes with the GROWTH Readiness Scorecard, sent straight to your inbox.