In previous research we have learned that patients with chronic or complex diseases often experience difficulties when transitioning from hospital care to self-care in their home. We address these difficulties by developing an eHealth tool for patients – ePATH (electronic Patient Activation in Treatment at Home) – intended to empower each patient to manage their individual situation. We have employed a user-centered design process involving both patients and healthcare personnel to specify the content and functionality of ePATH. The system is deployed as a web application with secure login for patients. In this article, we describe the main content and functionality of the system that makes it possible for a patient to manage symptoms development in relation to treatment progression Interactive functionality, e.g., reminders and social support, is included to make the ePATH a useful and informative bridge between patients, next-of-kin and different caregivers. One lesson learned is that it is necessary to incorporate motivational components in the development of an eHealth tool to successfully overcome the “intention-behavior” gap. The self-determination theory of motivation can be used to ensure that important aspects are not missed.