Fatigue is the most prevalent Long-COVID symptom. Individuals who are affected have to learn to organize and manage daily activities according to the subjectively perceived energy reserves. Our objective was to develop an application, Fading Fatigue, that supports patients in their energy management, in particular after an initial therapy guided by health professionals. Fading Fatigue was developed in an iterative approach and implemented as a client-server application. Interviews and a literature search were conducted to identify limitations and challenges of the current treatment. Fading Fatigue offers several tools for energy management: a daily energy planner, a documentation aid for well-being and a progress view. Future work should study usability. Inclusion of additional features increasing the adherence such as providing feedback could be considered.