Population ageing places significant pressures on health and social care services. Physical activity is one of the most promising avenues for reducing the socioeconomic burden of age-related diseases. Although mobile technologies could transform the healthcare industry, digital exclusion is stratified by socioeconomic status, emulating physical activity divides. My research will use methods such as multilevel modelling and machine learning to inform the development of a “just-in-time” adaptive intervention for older adults of low socioeconomic status. By monitoring dynamic biocultural variables (e.g. mood, physical/social environment), this digital intervention will aim to deliver personalised physical activity support when users need it most.