This paper describes the challenges and lessons learned in the experience-centered design (ECD) of the Spheres of Wellbeing, a technology to promote the mental health and wellbeing of a group of women, suffering from significant mental health problems and living in a medium secure hospital unit. First, we describe how our relationship with mental health professionals at the hospital and the aspirations for person-centric care that we shared with them enabled us, in the design of the Spheres, to innovate outside traditional healthcare procedures. We then provide insights into the challenges presented by the particular care culture and existing services and practices in the secure hospital unit that were revealed through our technology deployment. In discussing these challenges, our design enquiry opens up a space to make sense of experience living with complex mental health conditions in highly constrained contexts within which the deployment of the Spheres becomes an opportunity to think about wellbeing in similar contexts.