Put the stake outside your own head. Tell a colleague that if you are late to the meeting, lunch is on you.

What the research says

A cluster randomised trial across ten schools tested whether an intervention grounded in self determination theory changed pupils' intentions and their physical activity over five weeks. It shows that arrangements deliberately put in place can move behaviour, which is the general principle at work here. It concerned exercise in schools over a short period, so it says nothing about lunch bets between colleagues.

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