Three Good Things: The Exercise, and How to Do It
The three good things exercise involves writing down three things that went well each day, plus why each one happened, every night for about a week.
By Yagyesh Bobde · · Updated
The instruction is unusually specific for this genre. Not be grateful, not reflect on the positive. Write three things that went well today, and next to each one, write why it happened. Do that every night for a week.
That is the three good things exercise in full, and it comes from Seligman, Steen, Park and Peterson's 2005 paper in American Psychologist — a randomised, placebo-controlled internet study that tested five happiness exercises against a control writing task. Three of the exercises produced lasting increases in happiness and decreases in depressive symptoms. This was one of them.
The protocol, plainly
Four parts, and that is all of it.
- Once a day, at the end of the day, write three things that went well.
- For each one, write why you think it happened.
- Keep them specific — a moment you could picture again, not a category.
- Do it nightly for about a week, then decide whether to continue.
You can do it in a notebook, a note on your phone, or an app. The format was tested as free text, not as a rating or a tick box.
Why the "why it happened" half matters
It is the part almost everyone drops, and it is the part that changes what the entry does. "The deployment went through" is a record. "The deployment went through because I asked for a second pair of eyes on the configuration" is an explanation, and it names something repeatable.
Be clear on the evidence here, though. No study has separated the three-things half from the causes half, so nobody can tell you the attribution step is doing the work. It is part of the protocol that was tested, which is a weaker claim than it is the active ingredient.
Specific beats big
The most common way this goes wrong is aiming too high. People wait for three things worth reporting and find none, then stop.
The bar is much lower than that. "The chai someone made without being asked" is a moment you could still see a year from now. "Family" is a category, and categories are forgettable. Specificity is also what makes the entry worth rereading later, which is most of what savouring has to work with. On genuinely flat days, noticing at all is the practice.
What the evidence actually supports
Three findings, in descending order of reassurance.
The original 2005 study found lasting gains in happiness and reductions in depressive symptoms over six months, from one week of the exercise. That is the headline, and it is the reason anyone knows about this.
Mongrain and Anselmo-Matthews replicated it in 2012 with a tighter control design, and the picture became more modest. Happiness gains were replicated — but a "positive placebo" condition, designed only to make people access positive information about themselves, produced them too. The exercise did not outperform the control on depression. Their interpretation is that brief positive psychology exercises may work through a common factor rather than anything specific to the format, and that the depression effects are smaller than first assumed.
Looking at the wider picture, Bolier and colleagues' 2013 meta-analysis of 39 studies found standardised mean differences of 0.34 for subjective well-being, 0.20 for psychological well-being and 0.23 for depression across positive psychology interventions generally. Small effects, partly sustained at three to six months, with indications of publication bias and uneven study quality. Small and real is the accurate summary. Anything stronger is overselling.
The broader gratitude-listing finding sits alongside it. Emmons and McCullough's 2003 experiment found that people listing things they were grateful for reported more optimism and higher life satisfaction than people listing hassles.
How long, and does it keep working?
One week in the original study. Fifteen days in Sexton and Adair's 2019 pilot with healthcare workers, which reported improvements in emotional exhaustion, depressive symptoms and happiness at one, six and twelve months, with effect sizes from 0.16 to 0.52 — larger in the subgroup whose initial scores were in the concerning range. It was a pilot without a control group, so read it as encouraging rather than conclusive.
Beyond a few weeks, the honest answer is that nobody has measured it. What is predictable is that writing the same three categories every night stops feeling like noticing anything, which is ordinary hedonic adaptation rather than the exercise failing.
Where it usually fails
Not indifference. Adherence. Attrition is the recurring problem in these trials, and the same thing happens privately — the journal survives four good evenings and dies on the first bad one.
Which is the real argument for three rather than ten. A format you can finish in thirty seconds is one you will still finish the evening after you missed a day. If three is too many tonight, write one. One line written is worth more than a perfect entry you skipped.
Research
- Positive psychology progress: empirical validation of interventions — Seligman, M. E. P., Steen, T. A., Park, N., & Peterson, C. (2005)
- Do positive psychology exercises work? A replication of Seligman et al. (2005) — Mongrain, M., & Anselmo-Matthews, T. (2012)
- Forty-five good things: a prospective pilot study of the Three Good Things well-being intervention — Sexton, J. B., & Adair, K. C. (2019)
- Positive psychology interventions: a meta-analysis of randomised controlled studies — Bolier, L., Haverman, M., Westerhof, G. J., Riper, H., Smit, F., & Bohlmeijer, E. (2013)
- Counting blessings versus burdens: an experimental investigation of gratitude and subjective well-being in daily life — Emmons, R. A., & McCullough, M. E. (2003)
Common questions
What is the three good things exercise?
Every night before bed, write down three things that went well during the day, and next to each one write why you think it happened. Three items, one sitting, causes included. That is the whole exercise as it was originally tested, and the version in the 2005 study ran for one week.
How long should you do it for?
The original study asked people to do it for one week and then followed them for six months. A 2019 pilot with healthcare workers ran for fifteen days. Both are short. Nothing in the research says you have to keep it up forever, and nothing says a week is optimal either — a week is simply the dose that has been measured most.
Does it have to be three?
No. Three is a practical convention, not a research finding. None of the studies here compared three against two or five. Three is small enough that you will still finish it on an evening when you are tired, which matters more than the count, and one line is better than a skipped night.
What counts as a good thing?
Anything specific and true, not anything impressive. The chai someone made without being asked. A quiet walk home. One message that was well received. The test is whether you could still picture the moment a year from now. Categories like family or work are too vague to be worth writing.
Why do you have to write why it happened?
Because that is what the original instructions asked for, and it is the part most people drop. Writing the cause turns a list into an explanation — you end up noticing what you or someone else did to make the thing happen. No study has isolated that half of the exercise, so treat it as part of the tested protocol rather than a proven ingredient.
Does it stop working after a while?
The honest answer is that the trials were weeks long, so nobody has good data on year two. What is documented is that effects in the original study were modest, that a careful replication found a plausible placebo produced similar happiness gains, and that the practice tends to get repetitive if you keep writing the same three categories.
Is three good things the same as a gratitude journal?
It is one specific format of gratitude journal. A gratitude journal is the general practice of writing down what you are grateful for. Three good things fixes the count at three, adds the causes, and places the exercise at the end of the day.