Background: Self-directed therapy activities are not currently part of routine care during inpatient rehabilitation. Understanding patient and clinician perspectives on self-directed therapy is key to increasing implementation. The aim of this study was to investigate barriers and facilitators to implementing a self-directed therapy programme (“My Therapy”) in adult inpatient rehabilitation settings. Methods: My Therapy was recommended by physiotherapists and occupational therapists and completed by rehabilitation inpatients independently, outside of supervised therapy sessions. Physiotherapists, occupational therapists, and patients were invited to complete an online questionnaire comprising open-ended questions on barriers and facilitators to prescribing and participating in My Therapy. A directed content analysis of free-text responses was undertaken, with data coded using categories of the Capability, Opportunity, and Motivation Model of Behaviour (COM-B model). Results: Eleven patients and 20 clinicians completed the questionnaire. Patient capability was reported to be facilitated by comprehensive education by clinicians, with mixed attitudes towards the format of the programme booklet. Clinician capability was facilitated by staff collaboration. One benefit was the better use of downtime between the supervised therapy sessions, but opportunities for patients to engage in self-directed therapy were compromised by the lack of space to complete the programme. Clinician opportunity was reported to be provided via organisational support but workload was a reported barrier. Patient motivation to engage in self-directed therapy was reported to be fostered by feeling empowered, engaged, and encouraged to participate. Clinician motivation was associated with belief in the value of the programme. Conclusion: Despite some barriers to rehabilitation patients independently practicing therapeutic exercises and activities outside of supervised sessions, both clinicians and patients agreed it should be considered as routine practice. To do this, patient time, ward space, and staff collaboration are required. Further research is needed to scale-up the implementation of the My Therapy programme and evaluate its effectiveness.