Public health officials should collaborate more with psychologists and modify their exercise messaging.

Improving public health messaging could help people see all the ways in which they’re already getting physical activity in their everyday lives: walking, talking the dog out, or cleaning the house, for example.

Experiments conducted in America showed that low and liberal guidelines (from the Centers for Disease Control and Prevention) led people to adopt a more positive mindset. These positive mindsets led to higher self-efficacy measures. And those with high self-efficacy were more likely to be act...