How long do I have to do Three Good Things for?

The original study asked people to do it for one week, and measured effects up to six months later. In practice, treat it as a habit rather than a course — the point is that it is small enough to keep.

What if nothing good happened today?

Then write small. "The coffee was good." "A song I like came on." The exercise does not require your day to have been remarkable, and days where nothing obvious stands out are exactly the days it is most worth doing.

Should I write it in the morning or the evening?

The original instruction was before bed, looking back at the day. Evening is the natural fit because the day is complete. If evenings do not work for you, doing it the next morning about the previous day is fine.

Do I have to write why it went well?

It is the part most people skip and the part the study specified. Writing the cause is what turns a list into a reflection, and it is where the exercise does its work.

Is Three Good Things the same as a gratitude journal?

It is one particular, well-specified form of gratitude journaling. A gratitude journal can be anything from a list of blessings to a long diary entry. Three Good Things fixes the format at three items a day, each with a reason.

Three Good Things — the exercise, the research, how to do it

Most gratitude exercises are vague. Three Good Things is not. It has a fixed format, a specific origin, and a randomised trial behind it, which is unusual for anything in this territory.

What the exercise is

Every night, before you go to sleep, write down three things that went well that day. Next to each one, write why it went well.

That is the whole exercise. It was designed to be small.

The “why” is not decorative. In the original instructions, participants were asked to give a causal explanation for each event — what made it happen, what part you or someone else played in it. It is the difference between “had lunch with Sam” and “had lunch with Sam, because I finally suggested a date instead of waiting for them to”.

Where it comes from

The exercise was introduced in a 2005 paper in American Psychologist by Martin Seligman, Tracy Steen, Nansook Park and Christopher Peterson, titled “Positive psychology progress: empirical validation of interventions” (doi:10.1037/0003-066X.60.5.410).

The study ran five exercises against a placebo control, with participants randomly assigned. Three Good Things — the paper calls it the “gratitude visit” study’s sibling exercise, “three good things in life” — was one of two that produced effects lasting beyond the week of the intervention. People who did it reported higher happiness and lower depressive symptoms, and those differences were still measurable at the six-month follow-up.

Two things are worth being honest about. The participants were self-selected visitors to a positive psychology website, not a representative sample. And the paper’s own reading is that the people who kept doing the exercise past the assigned week were the ones who benefited most — which makes the size of the habit the important variable, not the size of the effect in week one.

Why the format works

It is bounded. Three items, not “write about your day”. You know when you are finished, which is what makes it possible to do on a bad night.

It is specific. “I am grateful for my family” is hard to write twice without it going stale. “My brother sent a photo of the dog wearing a hat” is a different thing every day, and it is the specific version that you can still picture a year later.

It ends on cause. Asking why something went well quietly makes you look for your own part in it, or someone else’s. Over weeks that adds up to a running record of what actually produces good days for you.

How to do it tonight

Pick a moment that already exists in your day — the last thing before lights out, or while the kettle boils.
Write three things that went well today. Short is correct.
For each one, add a few words about why it went well.
Stop. Do not review, do not rate the day, do not turn it into a diary.

Do that for a week and you will know whether it fits. The failure mode is never that the exercise is too hard; it is that people set themselves a paragraph a night and quit on day four.

Doing it on paper or in an app

Paper works. A notebook by the bed has no notifications and no account.

What paper does not do is bring the entries back. The reason to use an app is that a year later it can show you what you wrote on this date — which is the part of the habit most people find surprising, because the small things you wrote down are the ones you would otherwise have lost entirely.

MindHappy is built around exactly this exercise: three things a day, a streak so the habit has something to hold onto, one reminder at a time you choose, and On This Day memories that bring the entries back a year later. It is free, and you do not need an account to start.

The Three Good Things exercise