When I was writing Better Than Before, my book about how to make and break habits, one thing took me a long time to recognize: the danger of finish lines.

Setting a finish line does indeed help people aims toward and reach a goal, but although it’s widely assumed to help habit-formation, finish lines can actually undermine habits.

A finish line marks a stopping point, and once we stop, we must start over, and starting over is harder than starting.

And the more dramatic the goal, the more decisive the end—and the more effort required to start over.

So, by providing a specific goal, a temporary motivation, and requiring a new “start” once reached, hitting a finish line may interfere with habit-formation.

Also, once we decide that we’ve achieved success, we tend to stop moving forward.

Even an intermediate finish line can interfere with good habits. In a letter to his son Mark, renowned novelist Kurt Vonnegut advised:

I have seen a lot of writers stop writing or at least slow down after getting an advance. They have a feeling of completion after making a deal. That’s bad news creatively…I advise you to carry on without an advance, without that false feeling of completion.

Have you ever found that hitting a finish line meant that you stopped doing something, even though you’d been doing it successfully to that point? That you thought you’d been forging a habit, but it turned out not to be?

Finish lines can be dangerous.