Within the field of health research, the randomised controlled trial (RCT) is often highlighted as the best method for producing statistically valid evidence about the effects of health interventions. To produce evidence that is also socially relevant, health researchers increasingly perform trials outside the laboratory in people’s everyday lives. This creates a situation, in which scientific ideals of methodological rigour must be made to work with trial participants and their ongoing everyday lives. Jonas Winther’s dissertation, Making it Work, explores how this ambition is pursued in practice. The dissertation builds on Winther’s engagement as an ethnologist in an interdisciplinary research project in Denmark, which was structured around an intervention trial that tested the health effects of exercise in everyday life. Through ethnographic fieldwork among the participants and the researchers in the trial and a performative understanding of science, Winther examines the practical implementation of the trial protocol and how ideals of methodological rigour and everyday life workability are made to work together in different forms of trial work. By highlighting the everyday practices that form part of a health intervention project, the dissertation draws attention to the cultural norms, assumptions, and practices that constitutes the conditions of possibility for the production of evidence and lifestyle change. Overall, the dissertation broaches questions about how to design health intervention projects that can take into account the co-production of a health intervention and everyday life.