If-Then Planning: Write Implementation Intentions That Work
What 642 tests show about if-then plans: five evidence-based rules, 20 example plans for focus, health, study and money, WOOP, and when planning fails.
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On Sunday you decide to study every evening, run three times this week and stop opening Slack while you write. By Wednesday the intentions are intact and the behaviour isn't.
That gap is common: in the intention-behaviour reviews Gollwitzer and Sheeran summarise (2006), the median share of people who intended to act but did not was 47%, while only 7% of those who did not intend to act acted anyway. It usually happens in one moment: you miss the opportunity, meet it tired, or find something more interesting on screen. If-then plans, which researchers call implementation intentions, decide your response to that moment in advance. They are a modest but real nudge (d = .27 for behaviour change), best for small, cue-bound acts and little help for goals you don't care about.
What an if-then plan is: a situation linked to a response
Gollwitzer's 1999 paper in American Psychologist separates two kinds of commitment:
- A goal intention names an end point: "I intend to reach X." I want to finish my thesis.
- An implementation intention links a situation to a response: "When situation X arises, I will perform response Y." When I sit down at my desk after lunch, I will open the methods chapter.
Choosing the situation makes it easier to notice even when you're busy, and choosing the response ahead of time lets it start with little deliberation. In one study, students asked to write a report on Christmas Eve within 48 hours delivered on time three quarters of the time if they had also written down when and where, against one third of the rest.
How strong the evidence is: large in early studies, small but real in the field
Gollwitzer and Sheeran's 2006 meta-analysis pooled 94 tests (8,461 participants) and found d = .65 (95% CI .60 to .70) for goal attainment, which the authors call medium-to-large; d is the gap between groups in standard deviations.
A 2025 synthesis of 642 tests (Sheeran, Listrom and Gollwitzer, European Review of Social Psychology; studies from 1994 to September 2019) is more sobering. It is a different collection, not the 2006 estimate corrected:
- Behaviour change averaged d = .27 across 301 tests, against .47 for cognitive performance and .66 for regulating emotion.
- Lab effects were nearly double field effects (d = .49 vs .27).
- Publication bias was substantial. The raw average was d = .36; trim-and-fill barely moved it (.35), but a Bayesian model-averaged correction cut it to d = .15 (95% CI .08 to .22), though the data still favoured a real effect by about 319 to 1.
In plain terms (our conversion), d = .65 puts the average planner ahead of about 74% of non-planners (50% is no effect); for an everyday habit we'd expect d = .15 to .27, or 56% to 61%. Workplace samples averaged .26 (23 tests) against .39 for university students.
Two field experiments, side by side
| Flu-shot prompts (Milkman et al., PNAS, 2011) | Gym planning (Carrera et al., Journal of Health Economics, 2018) | |
|---|---|---|
| Sample | 3,272 employees of one US utility, 72.5% male, in 2009 amid H1N1 shortages | 877 gym members who completed a survey |
| Planners vs comparison | Wrote a date (or date and time) to attend an on-site clinic, vs no prompt (33.1% vaccinated) | Checked off planned workouts for the next 13 days, vs recalling the last two weeks |
| Result | Date and time: +4.2 points adjusted (95% CI 0.5 to 7.8, p = .03); date only: +1.5, not significant | No detectable effect: about 2.3 visits vs 2.6 (−0.30, 95% CI −0.71 to +0.11), though planners planned 7.04 and made 2.33 |
Pooled across five vaccination tests, the 2025 synthesis found d = .11 (95% CI −.06 to .28), so treat the flu-shot gain as promising, not settled.
Five rules for writing an if-then plan that fires
Note: These are across-study comparisons from the 2025 synthesis, not head-to-head experiments: direction, not precision.
- Write it as "If…, then I will…". Contingent plans beat schedule-style plans such as "Monday 7:00, gym" (d = .43 vs .29).
- Pick a cue you will certainly meet and notice. The 2025 authors found no cue type that stood out: a specific time and place averaged d = .46 (58 tests), a task juncture .50 (32), meeting a critical stimulus .49 (159), a time alone .25 (19, wide interval).
- Put one startable action in the then-part, chosen before you write the plan. Plans that also spelled out how or for how long you'd act had about half the effect of plain time-and-place plans (d = .24 vs .46). "Answer emails faster" decides nothing; "when the stand-up ends, I will reply to the oldest message" does.
- For a specific distraction, consider planning to ignore it. In one lab experiment (1999 review), "I will ignore it" beat "I will increase my efforts", which helped only at low or medium motivation. Pooled in 2025, ignoring (d = .48, 38 tests) matched cognitive procedures as a group (.48, 48 tests; concentrating alone .37, 6 tests): a tie-breaker, not a proven winner.
- Rehearse the plan once, then stop revisiting it. Rehearsal helped (d = .45 vs .33); more than one rehearsal added nothing, nor did visualising. Plans participants recorded, and so could revisit, did worse (d = .31 vs .44), which the authors read as deliberation undermining the automatic link ("rehearsed but not recorded" works best). Recording may be entangled with delivery mode (in-person .53, paper .35, online .31), so take it as a hint: write it once if that makes it specific, say it once or twice, then stop rewording.
Match the plan type to the problem you have
| If your problem is… | Plan type and template | d (tests, 2025) |
|---|---|---|
| You never find the moment | Opportunity: If it's [time] and I'm at [place], then I will [first action]. | .46 (58) |
| You start, then drift | Ignore: If [distraction] appears, then I will ignore it and [keep going]. | .48 (38) |
| An urge pulls you off course | Replacement: If I feel [urge], then I will [alternative]. | .27 (16) |
| Nerves at a key moment | Calm statement: If I notice [sign of nerves], then I will tell myself "[calm phrase]". | .69 (14); all inner speech .29 (28) |
| A setback knocks you out | Setback: If [setback], then I will [recovery step]. | .31 (17) |
The labels are ours; the d values come from different cuts of the data, so they are not a ranking.
20 example if-then plans for focus, health, study, and money
When participants chose their own cue the effect was small (d = .16, 20 tests), so swap in cues you will actually meet.
| If… | then I will… |
|---|---|
| Focus: I sit down at my desk after the 9:00 stand-up | open the draft and write one sentence before email |
| I notice I've opened a tab I didn't mean to | close it and return to the task |
| a notification appears during a focus block | ignore it until the block ends |
| someone asks "got a minute?" during a focus block | say "Can I find you at 11?" |
| I stop work for the day | write tomorrow's first step on a sticky note |
| Health: I get home from work | change into running clothes before sitting down |
| the dessert menu arrives | order a coffee |
| I pour my first coffee | take my vitamin D from the box by the kettle |
| rain cancels my run | do a 15-minute bodyweight routine indoors |
| I brush my teeth at night | put my phone on the charger in the hallway |
| Study: I sit down in the library after my 14:00 lecture | open the practice questions before my notes |
| I catch myself rereading the same page | close the book and write what I remember |
| I get a practice question wrong | log the right answer and why I missed it |
| my heart races as the exam paper arrives | tell myself "Stay calm, I've practised this" |
| a lecture ends | write a three-sentence summary before leaving |
| Money: my salary arrives | move €100 to savings first |
| my online basket goes over €50 | close the tab and wait 48 hours |
| a subscription renewal email arrives | cancel unless I used it this month |
| it's Sunday evening after dinner | log the week's spending in my budget sheet |
| I want to buy something to cheer myself up | add it to a wish list instead |
The 2025 review had two tests of a "notice I'm distracted" cue, so the stray-tab plan is the least proven, and it has no saving or spending category, so the money plans extrapolate. Closest to tested are the shutdown note (ending a phase of a task, d = .64 in 7 tests; see our guide to attention residue) and the 48-hour wait (waiting before responding, d = .66 in 7).
Find the real obstacle first: the WOOP exercise
A plan fails when it targets the wrong obstacle. WOOP (Wish, Outcome, Obstacle, Plan) is the everyday name for mental contrasting with implementation intentions (MCII), the technique Gabriele Oettingen and Peter Gollwitzer developed; a published trial calls WOOP "also known as" MCII. Mental contrasting means imagining the outcome you want, then the reality in its way.
The evidence is encouraging but modest. A 2021 meta-analysis (Wang, Wang and Gai; 21 articles) found g = 0.34, or 0.24 after correcting for publication bias. Experimenter-delivered exercises beat document-based ones (0.47 vs 0.28); doing it alone is probably closer to the latter, and that comparison left out two studies holding 87% of participants.
The steps, following the official WOOP site:
- Wish. One wish that is challenging but achievable. Finish the first draft of my conference talk by Friday.
- Outcome. Imagine the best result and how it would feel. Walking into Monday's rehearsal with a complete draft and no dread.
- Obstacle. Your main inner obstacle: your own reaction, not the circumstances. When I open the file, I feel the talk isn't good enough and switch to email.
- Plan. One if-then plan. If I feel the urge to switch to email while drafting, then I will write one more rough sentence.
If step 2 leaves you unmoved, choose a new wish; if step 3 shows the wish is out of reach, adjust, postpone or let it go. For an immediate problem the whole exercise can take about 30 seconds.
When if-then planning fails
The goal isn't strongly yours
Plans amplify motivation; they don't create it, and a plan for a goal you don't care about fails quietly. Across 64 physical-activity tests plans averaged only d = .14, but a post hoc median split of the 31 tests reporting intention scores found d = .31 when intentions were strong and about zero when weak, so the average mostly reflects who was recruited.
Too many plans aimed at one habit
In a 2013 study by Verhoeven and colleagues, summarised by the BPS Research Digest, 63 young women tried to cut snacking. Daily snacks fell from 2.01 to 1.47 with one plan and from 2.45 to 1.45 in a control group that only thought of healthy alternatives, but only from 1.95 to 1.83 with three plans (not significant): three plans failed, and one plan did not beat the control.
In a second study of 93 people, one snacking plan, and one snacking plan plus two academic plans, both led to faster responses to healthy-snack words than to bad-habit words; three snacking plans did not. That suggests competition between plans for the same habit, not between all your plans. The 2025 pooled data are messier (one plan d = .41, three .07, seven or eight about .41), so keep to one plan per habit until it fires without thought. The running-clothes and rain plans above are two plans for one habit.
Vague, rare, or impossible cues and actions
The 2006 review sets three conditions, and a plan that fails one usually fails quietly:
| Condition and test | Fails like this (for example) | Fix |
|---|---|---|
| Precise: could an observer tell whether the cue happened and what I did? | "If I have time tomorrow, I'll study." | "If I sit down after dinner, I will open the practice questions." |
| Viable: will the cue happen this week, and can I act when it does? | "If the train is empty, I'll read my notes." | "If I board the train, I will open my notes." |
| Instrumental: if I did this every time, would the goal move? | "If I open my laptop on Sunday, I'll tidy my files" (as a thesis plan) | "If I open my laptop on Sunday, I will open chapter 3." |
Where to start this week
- Choose one goal you want and expect to reach. If unsure of either, run a WOOP first.
- Write one plan with a cue you will meet this week and an action you can start in under a minute. Say it once or twice, then leave it alone.
- Count whether it fired. Of the times the cue came this fortnight, how many did you act on? "Nine of fourteen" beats a streak, which only shows the last gap (why habit trackers get abandoned).
- Review on Sunday. Count, don't reword: change the plan only if the cue never came, or came and you didn't act. A 20-minute weekly review fits here.
Goal (one, and one I want): ____________________
If [a cue I will certainly meet: a time and place, an event, the end of a task],
then I will [one action I can start in under a minute].
Frequently asked questions
Is habit stacking the same as an if-then plan?
Close. James Clear calls habit stacking "a special form of an implementation intention". Its cue is an existing routine; an if-then cue can also be a feeling, a distraction or a setback.
How quickly does an if-then plan start working?
In lab studies, straight away. In the 2025 data, outcomes within a week averaged d = .48 and the 12 tests with follow-ups of six months or more .51, though one-to-six-month follow-ups averaged .19. A plan is not yet a habit; how long habit formation takes varies widely.
Should I use an if-then plan or automate the task?
If a default can do the job, such as a standing order that moves money on payday, use it; it needs no cue. Keep if-then plans for moments that still need you to act. This is our reasoning, not research.
Sources and further reading
- Implementation intentions: Strong effects of simple plans — Gollwitzer, American Psychologist, 1999. Definition and early studies.
- Implementation intentions and goal achievement: A meta-analysis of effects and processes — Gollwitzer & Sheeran, Advances in Experimental Social Psychology, 2006. The d = .65 estimate.
- The when and how of planning: Meta-analysis of the scope and components of implementation intentions in 642 tests — Sheeran, Listrom & Gollwitzer, European Review of Social Psychology, 2025. Plan features, bias correction.
- Using implementation intentions prompts to enhance influenza vaccination rates — Milkman et al., PNAS, 2011. The flu-shot experiment.
- The limits of simple implementation intentions: Evidence from a field experiment on making plans to exercise — Carrera et al., Journal of Health Economics, 2018. The gym experiment.
- A meta-analysis of the effects of mental contrasting with implementation intentions on goal attainment — Wang, Wang & Gai, Frontiers in Psychology, 2021. Pooled MCII effect.