Everything counts in sending the right message: science-based messaging implications from the 2020 WHO guidelines on physical activity and sedentary behaviour.

The World Health Organization (WHO) released the 2020 global guidelines on physical activity and sedentary behaviour. The new guidelines contain a significant change from the 2010 guidelines on physical activity for adults and older adults that has important implications for next-generation physical activity messaging: The removal of the need for aerobic activity to occur in bouts of at least 10 min duration. This change in the guidelines provides an opportunity to communicate in new ways that align with behavioural science, permitting physical activity communicators and promoters to better support people's psychological needs, motivation, and ability to fit healthy levels of physical activity into their lives. The frames and messages we use to communicate about the guidelines matter because they influence whether activity is perceived as relevant, meaningful, and feasible - or not. When developing new physical activity communications there are some overarching principles, based on behavioural science, to keep in mind. Using established theory, this commentary aims to support the creation of more strategic frames and messages for increasing the value and integration of physical activity into daily living. Country-specific physical activity campaigns using these ideas will be discussed.