HabiterWhat happens if you miss a day of a habit?
Very little, according to the research. In the study behind the well-known "66 days" figure, missing a single day barely slowed progress and had no lasting effect. What matters more is what happens next: a broken streak can make people give up, even though the missed day itself cost them almost nothing.
What the study found
In the 2010 University College London study, participants missed their daily behaviour 140 times in total. On the day after a miss, how automatic the habit felt dipped by about 0.29 points, and progress across a missed day was smaller (0.55 points) than across three days without one (0.79). But there was no longer-term cost, and it made no difference when in the 12 weeks the miss happened. The authors' conclusion: a single missed opportunity did not materially affect habit formation.
Longer gaps are different. The authors point to earlier research in which missing a whole week of exercise predicted lower attendance later — so one day off is fine, a lapse that stretches on is worth catching.
Why a broken streak still feels bad
A 2023 set of seven studies found that people shown an intact streak engaged more afterwards than people shown a broken one — regardless of how they had actually behaved. The drop was larger when people blamed themselves for the break, and smaller when the streak could be repaired.
Dieting research describes a related pattern: once people believe they've already slipped, some give up on the rest of the day — the so-called "what-the-hell" effect. One missed day only becomes a problem if it turns into two.
Planned slack helps
- Emergency reserves: goals that came with a small number of allowed skips were preferred and increased persistence.
- Rewarding the comeback: in a megastudy of 61,293 gym members testing 54 programmes, the best-performing one gave a small reward for returning after a missed workout.
- Fresh starts: gym visits were more likely at the start of a week (+33.4%), a month (+14.4%) or a semester (+47.1%). You don't have to wait for Monday — but if Monday helps you restart, use it.
What to do after a missed day
- Do the habit at the next usual moment, even a smaller version of it. The goal is to keep the cue and the action linked.
- Don't make up for it by doubling tomorrow; just return to normal.
- If you know a busy day is coming, plan the skip in advance instead of breaking the habit by surprise.
- Look at the month, not the day. A calendar with one gap and 29 ticks is a habit forming.
How Habiter handles a missed day
Your streak never breaks before the day is over. If you did the habit but forgot to tick it, you can fill the day in afterwards — up to 5 days back on the free plan, any day with Pro. Habits can be planned for specific weekdays or every few days, so rest days don't count as misses.
With Pro, streak freezes let you skip a planned day without losing your streak — a built-in version of the "emergency reserve" above — and a comeback plan lets you decide in advance how you'll restart after a missed stretch. We make Habiter.
Sources
- Lally, van Jaarsveld, Potts & Wardle (2010), How are habits formed: Modelling habit formation in the real world. European Journal of Social Psychology 40(6) — doi.org
- Silverman & Barasch (2023), On or off track: how (broken) streaks affect consumer decisions. Journal of Consumer Research 49(6) (abstract) — doi.org
- Sharif & Shu (2017), Nudging persistence after failure through emergency reserves. Journal of Marketing Research 54(3) (abstract) — doi.org
- Milkman et al. (2021), Megastudies improve the impact of applied behavioural science. Nature 600 (abstract) — doi.org
- Dai, Milkman & Riis (2014), The fresh start effect: temporal landmarks motivate aspirational behavior. Management Science 60(10) — doi.org
- Gardner, Lally & Wardle (2012), Making health habitual: the psychology of 'habit-formation' and general practice. British Journal of General Practice 62(605) — doi.org