Many chronic conditions can be better managed by patients themselves with the use of decision support tools. This becomes even more necessary in the case of multimorbidity (i.e. presence of multiple chronic diseases) or in conditions where several underlying risk factors need to be managed and monitored in order to avoid relapse or the reoccurrence of an event, like in the case of stroke. However, despite the fact that these decision support systems are becoming prevalent, little is known about the best practices in designing for end-users - patients and their carers. The aim of the present paper is to report on the process of involving users to inform the design of a novel data-driven self-management mobile decision support tool for stroke survivors, called CONSULT. User involvement was facilitated through the use of a two-phase participatory design approach. During both phases a total of 44 stakeholders participated, including stroke survivors, carers, healthcare professionals and researchers. The paper documents the findings of the participatory design process, in the form of design recommendations, and describes their implications for user interface design.