Missed a day of your habit? Here's what actually happens.
Short answer: almost nothing. One missed day doesn't undo the work you've put in. What matters is what you do the day after.
The research: one missed day didn't change the result
In 2010, researchers at University College London followed 96 volunteers who each picked a new daily habit, such as eating fruit with lunch or going for a run before dinner. Every day for 12 weeks, people logged whether they'd done it and how automatic it felt.
The finding most people remember is how long habits took to form (more on that in our guide to habit timing). The finding that matters here is quieter: missing a single day did not materially affect how the habit formed. People who slipped once and carried on ended up in much the same place as people who didn't slip.
Source: Lally, van Jaarsveld, Potts and Wardle, How are habits formed: Modelling habit formation in the real world, European Journal of Social Psychology, 2010.
Why one missed day feels so much bigger
If one day makes so little difference, why does it feel like a disaster? Usually it's not the day itself, it's how we count it. Many people think of a habit as an unbroken chain, so one gap feels like losing everything and starting again from zero.
That all-or-nothing thinking is what does the damage. The missed day costs you almost nothing; deciding "I've blown it" and stopping altogether costs you the habit.
What to do the day after
Do the smallest version. If your habit is a 30-minute walk, a 5-minute walk still counts as showing up. The aim is to keep the routine alive, not to make up for lost time.
Don't double up. Trying to do two days' worth turns tomorrow into a punishment, which makes the day after that harder.
Look at the bigger picture. Ten days done out of the last twelve is good progress. Judge the month, not the day.
Plan for the next rough day. Decide now what a minimum day looks like, so the next time life gets in the way you already know what "enough" is.
Plan for days off on purpose
Illness, travel and long shifts are going to happen. Building a few days off into your plan in advance means a bad day is something you expected, not something you failed at.
That's the idea behind Flaric, the iPhone habit tracker we make. When you miss a day, it offers you a day off so you keep your progress instead of going back to zero, and your calendar still shows honestly what happened. You decide whether to use it; it's never applied for you.