The Three Good Things Exercise: How It Works and What the Study Found
Updated: 1 day ago
Three Good Things may be the simplest well-being exercise ever tested in a randomized trial. Each night, you write down three things that went well that day and why they happened. That is the whole thing. No special notebook, no affirmations, no meditation.
It became famous because of one study, and that study has a detail most summaries leave out: the people who benefited most were the ones who kept doing it after they were told they could stop.
The original study
In 2005, Martin Seligman, Tracy Steen, Nansook Park and Christopher Peterson published a random-assignment, placebo-controlled internet study in American Psychologist. They tested five happiness exercises against one placebo exercise, each lasting one week.
The Three Good Things instructions, as described in the paper: participants were asked "to write down three things that went well each day and their causes every night for one week," and to give a causal explanation for each good thing.
The placebo was journaling about early memories every night for a week. The other exercises included a gratitude visit (writing and delivering a thank-you letter in person) and several exercises about personal strengths.
Participants filled in a happiness questionnaire and a depression symptom scale at the start, right after the week, and then one week, one month, three months and six months later.
The numbers, worked through
Here is the study's flow, with our arithmetic at each step.
577 adults completed the starting questionnaires. They were visitors to the website for Seligman's book, recruited over about a month.
411 of them, or 71 percent, completed all five follow-ups. That means 577 minus 411, or 166 people, dropped out somewhere along the way, even though finishers were entered into a prize lottery.
With 411 finishers spread across six groups, the average group had about 68 people.
One week of the exercise means 7 nights times 3 good things, or 21 entries in total. That was the entire required dose.
And the results:
Everyone, including the placebo group, felt a bit better right after the first week. By one week later, the placebo group was back to baseline and stayed there.
The gratitude visit produced the largest immediate boost in the whole study, but by three months it had faded back to baseline.
Three Good Things started slowly. Its benefits showed up at the one-month follow-up, and participants were still happier and reported fewer depressive symptoms than at baseline at three and six months.
The detail that matters most
Why would a one-week exercise show effects six months later? The authors checked. At each follow-up they asked whether people had kept doing the exercise on their own. Those who continued were the happiest, and the long-term effects "were most pronounced for those who continued the exercises on their own." The authors noted that most participants in the Three Good Things condition said they were still doing it.
Our computation: if you kept going at the study's pace, 21 good things a week becomes 3 times 365, or 1,095 good things in a year. The study's lesson is that the 21 are a sample. The habit is the part that seems to carry the benefit.
Keeping the claims modest
This study is a starting point, not proof of a miracle. The authors themselves flag the limits: the sample was self-selected from a happiness website, 77 percent White, and highly educated, with only 4 percent lacking any education beyond high school. People who seek out happiness exercises may respond differently from everyone else.
Later research is also more cautious. A meta-analysis by David Cregg and Jennifer Cheavens, covering 27 studies and 3,675 participants and summarized by Ohio State, found only "a small difference" on depression and anxiety symptoms when gratitude exercises such as Three Good Things were compared with other activities. The authors said it "would not be something you would recommend as a treatment."
So treat Three Good Things as what it is: a pleasant, low-cost way to notice your day. It is not mental health care. If you are in crisis, call or text 988.
How to do it well
The study gives a few practical cues.
Do it at night. The original instructions were every night, looking back over the day. Evening gives you a whole day to draw from.
Small counts. A good thing does not need to be a promotion. A long walk, a quiet coffee, a kid laughing at dinner all qualify.
Add a why when you can. The original exercise asked for causes. "My kids laughing at dinner, because we finally put the phones away" turns a moment into something you understand about your own life.
Keep going past week one. This is the step that made the difference in the data, and it is the step most people drop.
Doing Three Good Things by text
Gratitude Textapp is an AI journal that runs the evening part for you. Each night at 8pm, or a time you pick, it texts asking for one to three things you are grateful for. You reply in your own words, it saves the entry, and it answers with one short line that picks up what you wrote. If you already wrote that day, it skips the prompt.
App (8pm): Gratitude time from your AI journal: What's something good, big or small, from today?
You: my kids laughing at dinner, a long walk
App: Kids laughing at dinner and a long walk, those small joys add up.
Because entries are saved, you can later ask it to show you a good moment from before, or ask for your streak and the themes you write about most, like family, nature or food. It is an AI, not a person or a therapist, and it can get things wrong.
Try it by text
Text Hi to (872) 999-4985. From then on, each evening it texts you a prompt asking what went well, and you answer with one, two or three good things in your own words. You can move the time whenever you like by asking it.
It works on any phone that can text, with no app and no account. Your first 20 messages are free, then one $9.99/month subscription covers every Textapp. Entries are stored by Textapp to run your journal and are not shared or sold. Message and data rates may apply. Text STOP at any time to end messages. More at textapp.co/apps/gratitude.
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