Implementation intentions: the one-sentence plan with unusually strong evidence

An implementation intention is a simple plan written as one sentence: "If X happens, then I will do Y." Peter Gollwitzer at New York University published the key paper on the idea in 1999, and a 2006 meta-analysis by Gollwitzer and Paschal Sheeran, covering 94 independent tests, found a medium-to-large effect on people reaching their goals. For something that takes about two minutes to write, it's one of the best-evidenced tools in PiViva.

Why do good intentions fall apart at the last moment?

You meant to go to the gym after work. Then six o'clock came round, you were tired, somebody asked you a question on the way out, and the moment passed without you ever really deciding not to go.

The same thing happens with the call to the plumber, the report you were definitely going to start this morning, and the promise to yourself that next time you'd say no. The intention was completely real, and you genuinely wanted to do it, which makes it all the more frustrating when it slips away.

What was missing was a decision made in advance about exactly when and how. Without that, every good intention has to compete with whatever else is happening at the time, and the thing in front of you nearly always wins.

What are implementation intentions, and where did they come from?

Peter Gollwitzer, a psychologist at New York University, published "Implementation intentions: Strong effects of simple plans" in American Psychologist in 1999. His idea was a simple one. A goal describes what you want, while an implementation intention spells out when, where and how you'll act on it, in the form "If [situation], then I will [action]."

The evidence behind it is unusually strong for something so small. In 2006 Gollwitzer and Paschal Sheeran brought together 94 independent tests of the idea and found a medium-to-large effect on goal attainment. Studies have looked at exercise, healthy eating, voting, vaccination, revision for exams and a good deal more.

The reason it works is quite reassuring. You make the decision at a calm moment, ahead of time, so you don't have to make it later when you're tired, distracted or tempted by something else. The situation itself becomes the reminder, and the plan kicks in almost automatically.

How do you write an implementation intention in PiViva?

You write one sentence, "If X happens, then I will do Y," and attach it to a habit or an action. You can come back and write a fresh one whenever you need it.

The effect depends on writing it well, so the "if" needs to be a specific situation you'll actually notice. "If I feel like skipping the gym" is quite hard to catch, because feelings tend to creep up on us, whereas "if it's Tuesday at six and I'm still at my desk" is a moment you'll recognise straight away.

The "then" works best as a single, concrete thing you can do. "Then I'll pack up and walk to the gym" gives you something clear to act on, while "then I'll be more disciplined" leaves you more or less where you started. One sentence and two minutes of thought gives you better odds than almost anything else you could do with that time.

What if your plan still doesn't happen?

Take another look at the "if". More often than not it's a little too vague, or it describes a situation that doesn't come up often enough to be useful, and a small adjustment is all it needs.

You can also write a plan for the obstacle itself. "If I get home and want to sit down, then I'll put my trainers on before I take my coat off" is the sort of plan that gets you past the moment where things usually go wrong. That's the same idea used in WOOP, which adds a step to help you find the obstacle first.

Implementation intentions also sit inside the Weekly Success Planner, where you name the distractions you expect each week and decide how you'll handle them. Little by little, these small plans can turn the things you keep meaning to do into things you simply do, and that steady sense of following through is one of the most encouraging feelings there is.