Today's demographic changes with the rising number of the elderly require new forms of health promotion and innovative approaches to increasing physical fitness. Physical activity is considered as one of the key factors of ageing healthy and at the same time one of the key motivational challenges for the elderly. Supporting healthy ageing through sustained physical fitness requires interventions that promote healthy levels of physical activity as part of everyday life. Wearable devices, such as activity trackers or smart wristbands, are body-worn and may be seamlessly integrated into everyday activities to track fitness data, thus bearing the potential of supporting healthy living habits at older age. Although wearable technologies have been used by younger adopters to optimise physical fitness, little is known so far how these emerging technologies may be leveraged to improve well-being and overall fitness of seniors. In this paper we present the multi-layer approach to designing for user user engagement in wearable-technology enhanced learning for healthy ageing as part of an R&D project called “Fitness MOOC – interaction of seniors with wearable fitness trackers in the MOOC (fMOOC)”. fMOOC is a wearable-technology enhanced learning solution combining the MOOC (Massive Open Online Course) approach with embodied learning experience enhanced by wearable activity trackers used to track and monitor physical activity of senior learners. The paper proposes an adaptation of a standard User Experience (UX) model to the context of learning and instructional design and describes how methods for user engagement design have been applied on five different levels, i.e. conceptual, requirements, instructional, architecture and interface design, in the fMOOC project.