A new practice needs somewhere to live. Hook it to something you already do a few times a day, like sitting down to eat.

What the research says

In a randomised comparison of ways to get young adults eating more fruit and vegetables, plans that tied a specific situation to a specific response did better than vaguer general ones. It was an everyday eating behaviour in a young sample, so the size of the effect is not the point. The design lesson is what transfers: name the cue, name the response.

Strength of evidence: one line of research. A single study, or a theoretical account.