Missed a day? Why one slip won’t break your habit

Short answer: one day is almost nothing

A habit isn’t a chain that snaps at a single link. It’s more like a path worn into the grass: one day without walking it won’t let it grow over. The Lally et al. study backs this up — after a single miss, the automaticity of the behavior barely moved on average.

The trouble starts elsewhere. Psychology describes two related phenomena: the abstinence violation effect and the “what the hell effect.” Both describe how a single stumble can turn into the end of the whole plan. And you can prepare for both.

What happened in the study after a missed day

The Lally et al. study followed people building a new daily habit for 12 weeks. How many days it took and what “plateau” means is covered in How long does it take to form a habit? Not 21 days. Here, we’re interested in a different part: what a single missed day did.

The authors looked for situations where someone did the behavior three times in a row and then skipped it. They found 140 such misses in 55 people. Right after the miss, automaticity dropped by an average of 0.29 points on a 0–42 scale — next to nothing.

Even more interesting is what came next. In the 67 cases where the behavior was done again the next day and data were available, the score was 0.55 points higher than before the miss (not a statistically significant difference). For comparison: three days in a row with no miss added 0.79 points over the same period. The authors call the two increases comparable and conclude that a single miss had no lasting cost.

No link was found with whether the miss came early on or later. But the authors note that there were few cases and the question needs more research.

One day isn’t a week

Lally et al. set their result alongside an older study, Armitage (2005), which followed 94 people for 12 weeks after they joined a gym. There, a lapse meant a whole week without a visit, and such lapses predicted worse exercise afterward. According to the authors, both results suggest that a single missed opportunity doesn’t rule out habit formation, while a week of lapses lowers the chance of keeping going and slows habit formation.

Where exactly the line is, nobody knows. The authors themselves write that the level of consistency needed isn’t yet known.

Why one day hurts more than it should

The abstinence violation effect

Psychologist G. Alan Marlatt and his colleagues described this concept in their relapse prevention model, which was developed for treating addiction. The model distinguishes between a one-off slip and a full return to the old behavior — and says the first doesn’t necessarily lead to the second. According to an overview by Larimer, Palmer and Marlatt (1999), whether a slip turns into a full return can depend in part on how a person explains it to themselves.

According to the model, someone who blames a slip on a permanent trait outside their control (“I have no willpower and I’ll never manage this”) is more likely to give up the whole attempt. Someone who puts it down to a specific situation they can handle differently next time has a chance to learn from it. The model was developed for addiction, not walking, so this is an analogy — but the principle of how you explain a slip to yourself fits.

The “what the hell effect”

Psychologists C. Peter Herman and Janet Polivy have spent decades studying dieters. When dieters’ rules get broken — for example, when they’re led in the lab to eat something that breaks their diet — they often abandon the diet entirely, at least for a while. Herman and Polivy called this the “what the hell effect”: the diet is blown anyway, so I might as well enjoy it. With a streak, you can imagine similar reasoning — it’s gone, so why walk today at all? But Herman and Polivy didn’t study streaks directly.

A broken streak in an app

Silverman and Barasch (2023) looked at a 30-day university challenge with a goal of 7,000 steps a day, in which 980 employees took part. The app showed them how many days in a row they’d hit the goal. After a broken streak, people hit the goal less often than with an unbroken one. But these are correlational data, and the authors themselves note that the effect of the streak itself can’t be cleanly separated out.

Follow-up online experiments showed two things. The drop was stronger when people blamed themselves for the break. And when a broken streak could be repaired, the drop was smaller: in a simple game with 601 participants, about 93% of people with an unbroken streak stuck with the same type of game, compared with 69% with a broken streak and 85% with a broken but repairable one. Why streaks motivate in the first place is explained in Why streaks work (and when they stop working).

What to do when a day doesn’t work out

1. Name the cause specifically. “On Wednesday the meeting ran until seven, and then it rained” is more useful than “I have no willpower.” A specific cause can be fixed; a character flaw can’t.
2. Don’t miss two days in a row. The “never miss twice” rule is a popular rule of thumb, not a study finding. But it fits well with what we know: a single miss didn’t matter, while a whole week was linked to worse follow-through.
3. Lower the bar the next day. Ten minutes around the block is enough. The goal isn’t to make up the loss by doubling up, but to get back into your rhythm.
4. Go back to the same cue. In the study, habits formed through repetition in the same situation. If you usually walk after lunch, walk after lunch again.
5. Plan for predictable gaps. Travel, illness or a crunch at work will come. Relapse prevention therapy works with a plan for slips prepared in advance — like an emergency kit you may never need to open. On a trip, for example, a walk right after you arrive; when you’re sick, rest. For more serious health problems, the right person to ask is your doctor.

If the slip coincides with a January resolution that’s starting to crumble, How to stick with exercise after your New Year’s resolution may help too.

How Tada! handles missed days

Tada! counts active days: 6,000 steps or 20 minutes of workout from Apple Health or Health Connect. It plans for missed days from the start, because they happen even to the most consistent people.

• A day doesn’t close until noon the next day. So a late sync from your watch usually won’t break your streak.
• A freeze is used automatically. It holds your streak but doesn’t add the day. Free gives you 1 a month, Plus 4. They don’t add up.
• Repair within 48 hours. Once your freezes are used up, you can still repair a missed day within 48 hours of the day closing — but only one. Plus includes one repair a month. You can’t repair more days back; otherwise a streak could be bought and would stop meaning anything.
• If nothing works out, your streak starts again from zero. But your longest streak stays as your best, and the calendar keeps every day you actually completed.

The details are in the help article Freezes.

One bad day doesn’t have to cost you your streak Tada! holds your streak with an automatic freeze, and a missed day can be repaired within 48 hours. No sign-up, no ads. Download for iPhone

Frequently asked questions

Do I have to start my habit from scratch after a slip?

No. The streak number in an app may reset to zero, but the habit in your head doesn’t. In the Lally et al. study, automaticity barely changed after a single miss.

How many misses are too many?

Nobody knows the exact line. In the study, one missed opportunity didn’t matter; in another study, a week without going to the gym was already linked to worse follow-through. A safe strategy: don’t let a slip drag on.

Does a “safety net” for a missed day actually help?

An experiment from Silverman and Barasch suggests that being able to repair a broken streak softens the drop in people’s willingness to keep going. But it was a short online game, not long-term exercise.

Sources

1. Lally, P., van Jaarsveld, C. H. M., Potts, H. W. W., Wardle, J. (2010, online 2009). How are habits formed: Modelling habit formation in the real world. European Journal of Social Psychology, 40(6), 998–1009. doi:10.1002/ejsp.674
2. Armitage, C. J. (2005). Can the theory of planned behavior predict the maintenance of physical activity? Health Psychology, 24(3), 235–245. doi:10.1037/0278-6133.24.3.235
3. Larimer, M. E., Palmer, R. S., Marlatt, G. A. (1999). Relapse prevention: An overview of Marlatt’s cognitive-behavioral model. Alcohol Research & Health, 23(2), 151–160. PMC6760427
4. Polivy, J., Herman, C. P. (2020). Overeating in restrained and unrestrained eaters. Frontiers in Nutrition, 7, 30. doi:10.3389/fnut.2020.00030
5. Silverman, J., Barasch, A. (2023, online 2022). On or off track: How (broken) streaks affect consumer decisions. Journal of Consumer Research, 49(6), 1095–1117. doi:10.1093/jcr/ucac029
6. Tada! Help. Freezes; Missed day and repair; Waiting for data. tadapp.eu