The urban population of cities world-wide is steadily growing, causing pressure on land use for different purposes, such as residential, commercial, or recreational use. A growing urban population will also create new public health challenges, especially due to the epidemic increase of Non-Communicable Diseases. Creating opportunities for and increasing physical activity in public open spaces could represent a crucial resource to tackle health problems of urban residents. This multiple case study explores the strategies and approaches of two case cities (Malmö and Copenhagen) in connection to planning for physical activity in public open spaces and the collaborative efforts behind it. The empirical material for the study consists of 9 interviews with professionals connected to urban planning from the municipalities of Malmö and Copenhagen. The collaborations between urban planners and other actors were analysed using collaboration theory. Various barriers and facilitators of collaboration were identified, as well as findings which can suggest more fruitful collaboration.