ObjectivesTo establish proof of concept of a prehabilitation intervention, a combination of education and behavioural change, preceding a physical activity programme in people with fibromyalgia (FM).SettingsOpen-label, feasibility clinical trial.ParticipantsEleven people with FM (10 women).InterventionsThe prehabilitation intervention consisted of 4 weeks, 1 weekly session (~1 to 1.5 hours), aimed to increase self-efficacy and understand why and how to engage in a gentle and self-paced physical activity programme (6 weeks of walking with telephone support).Primary and secondary outcome measuresPrimary outcome was the acceptability and credibility of the intervention by means of the Credibility/Expectancy Questionnaire. Secondary outcomes comprised scales to measure FM severity, specific symptoms and sedentary behaviour. An exit interview was conducted to identify the strengths and weaknesses and barriers to the intervention.ResultsOne participant dropped out due to finding the walking programme excessively stressful. Participants expected the intervention would improve their symptoms by 22%–38% but resulted in 5%–26% improvements. Participants would be confident in recommending this intervention to a friend who experiences similar problems. The interviews suggested that the fluctuation of symptoms should be considered as an outcome and that the prehabilitation intervention should accomodate these fluctuation. Additional suggestions were to incorporate initial interviews (patient-centred approach), to tailor the programmes to individuals’ priorities and to offer a variety of physical activity programmes to improve motivation.ConclusionsThis feasibility study demonstrated that our novel approach is acceptable to people with FM. Future interventions should pay attention to flexibility, symptoms fluctuation and patients support.Trial registration numberNCT03764397.