If you listen to most public health messages they are framed in the negative for the intervention and for the outcome: “Don’t do this so that you won’t get that.” For example, my pregnant wife was told by the Department of Health “Don’t drink wine to avoid damage to the baby.”

Now at one level I cannot criticise such messages. They are accurate, and they link an action and a consequence. They may even be evidence based, although I am already old enough …