Low-carbon lifestyles – from eating less meat, swapping a car for a bike, and switching to energy efficient devices – can help reduce greenhouse gas emissions. The EU-funded CAMPAIGNers project aims to revolutionise the way lifestyle transformation research is conducted and how it informs policies. Specifically, it will move from hypothetical citizen behaviour to the implementation of a goal-setting network where multiple thousands of citizens receive and create challenges to try out tailored adaptations to their daily routines via an engaging app. The project identifies the barriers and enablers across five continents and 13 major cities. The findings will be used to design feasible pathways to reducing greenhouse gas emissions.