At the end of a workshop in 1997, I offered a clichéd end-of-training activity: “How will you use what you’ve learned in this workshop? Write that down.” A few people started to write. More people looked uncomfortable. More than half seemed to check out mentally, and two began to check out physically, gathering their belongings to leave.

In the spur of the moment, I invented an elaboration: “What one small thing will you commit to doing? What’s the smallest thing you can commit to?”

One man asked, “How small?” I said, “Smaller than that.” He laughed, because my kinda non-answer answer seemed funny. Then he immediately thought of something. “Aha!” he said, and started to write. Another man still didn’t understand, so I offered a bound: “Something you could do all on your own before noon on Monday.” That made sense to him, and he began to write. And everybody else wrote. The two people who had started to gather their belongings sat down and wrote.

That spontaneous refinement worked so well that I now often end workshops with the One Small Thing activity: What one small thing will you commit to doing? Something you could do all on your own before noon? Write it down.

Over the years I’ve learned what makes this simple activity so powerful. First, people can almost always find something to commit to. If they are reluctant to commit to a given action, there’s almost always a smaller action that they will commit to fully, with enthusiasm. One small thing. How small? Smaller than that. What kind of thing? Anything that you will commit to.

Second, when invited to commit to one small thing, people always find something that matters to them. So small doesn’t mean unimportant.

Third, people are good at keeping small commitments. Keeping one small commitment starts a ball rolling—or continues one, for people who already make and keep personal commitments.

Fourth, once people see that keeping even a small commitment has good effects, and feels good in and of itself, they realize that they can make their lives better even in small steps.

When people finish writing, I invite them to share their commitments if they wish. Almost always there’s a pause. Then someone shares. Then someone else. After the first few, other people begin to feel safer. Usually about a third of the people in the room will share their commitments, and then we’re done.

As I invite people to share, I make it clear that sharing is entirely voluntary, and that it’s okay to keep these commitments private and personal. At a recent workshop, one woman approached me after the activity and said, “Originally I wrote down something I didn’t really care about. When I saw that you really weren’t going to make us say our commitments out loud, I realized that this wasn’t for you, it was for me. So I changed my commitment to something that matters to me. It matters a lot.”