Background: Physical inactivity is prevalent among hospitalized patients and the daytime spent lying should be utilised for exercise. However, implementing new interventions in hospitals' complex daily routines is difficult and requires a participatory approach. Objective: Exploring clinical settings and clinicians' perspectives regarding exercise in hospitalized patients to gauge the potential of further development of an in-bed training device and to formulate development goals. Methods: A User-Centered Design approach was employed, consisting of work shadowing and focus groups with physiotherapists and nurses. Content and network analyses of the focus group data were performed. Personas were then developed and used to create clinical scenarios. Results: Some clinicians perceived in-bed exercise counterproductive, while others recognized potential for unsupervised training. The most important design characteristics appeared to be a small size, low weight and simplicity of use to facilitate storage, transportation, and administration, respectively. The scenarios revealed that the device's use could increase the physical activity time by 1.4%, although it would also increase the working time of clinicians. Conclusion: The study highlighted the difficulties in developing a usable training device but encouraged the authors to pursue their efforts under the strict condition of following the formulated development goals.