Most of us value our health highly yet act in ways that undermine it. If we ate and drank less, didn’t smoke, and were physically more active, 40% of cancers and 75% of diabetes and cardiovascular disease would be avoided. Because these behaviours tend to cluster by deprivation, achieving these changes for everyone could also halve the gaps in life expectancy and years lived in good health between the rich and the poor. In the UK, around 16% of the population smokes, the lowest figure for many decades, although among those who are poorest this rate is doubled. About 25% of those who consume alcohol do so at a rate considered harmful. Excessive eating explains much of why 65% of the population is overweight or obese. But our rates of inactivity top the lot: when measured objectively (rather than by our more generous self-reports) around 95% of us can be deemed “inactive” by failing to meet the guideline of 150 min of moderate intensity physical activity each week. Changing all these behaviours will need many different interventions operating at the same time. Critical will be the use of interventions that are effective at scale and with the potential to reach the entire population.