In solving systemic design challenges designers co-create with professionals from various fields. In the context of innovation in healthcare practices, this study investigates design abilities that healthcare professionals develop by participating in co-design projects. We conducted a mixed-methods research approach consisting of five retrospective interviews with healthcare researchers involved in co-design projects, and a multiple case study (three cases) on the collaboration between design researchers and healthcare professionals. The three cases all aimed at designing tools for healthcare innovation. The cases differ in the healthcare context and the professionals involved: Paediatric physical therapists in the treatment of babies (0-2 years), supervisors (e.g. in assisted living) of people with intellectual disabilities, and academic researchers in social sciences and design research developing e-health applications for elderly people with early stages of dementia. Literature states that healthcare professionals may be competent in specific abilities related to design, but they are not trained to mode-shift and to use two different ways of working for creativity. We found that the healthcare professionals involved in co-design projects developed design ability over time, and that the research setting was supportive. Based on design abilities that the five healthcare researchers explicated in the interviews as having adopted, we suggest eight mode-shift practices related to design, which we investigated in the cases. Findings of the case-study show that two mode-shift practices related to design and innovation are difficult to adopt for healthcare professionals: Generate and synthesize; and keeping track on overview and details. These two design abilities require more training and/or experience than the other six design abilities that ran smoothly in the cases, if healthcare professionals were facilitated in the process. Healthcare professionals specifically relate two of these practices to design: Collaboration and slow down – sprint. This study discusses these findings by referring to an analogy of kayaking on a wild water river: The collaboration aspect of switching between working in a group and by yourself, like a group of kayakers who collaborate in going down stream a river but peddle by themselves in their own boats; the slowdown and sprint aspect, like kayakers who oversee the river in turning waters and sprint in between, rather than go with the flow in a raft.