PRECIOUS: PREventive Care Infrastructure based On Ubiquitous Sensing will provide a preventive care system to promote healthy lifestyles, which is comprised of three components: (1) transparent sensors for monitoring user context and health indicators (food intake, sleep and activity) deliver ambient data about current user behavior; (2) users are represented by individual virtual models which allow inferring health risks and desired behavioral changes; (3) state-of-the-art motivational techniques originating especially from gamification and motivational interview trigger a set of feedback tools to change the user habits toward more healthy conduct.While related projects usually focus on developing specific sensors, middleware solutions, health monitoring systems, eHealth services, etc., both the individual virtual model and the associated motivational tools will now provide key innovation steps towards a preventive care system with measurable impact on user behavior and thus a clear potential for large scale commercialization and sustainable societal footprint (e.g. with respect to cost saving in the public health sector as well as life quality improvements).To reach these goals, PRECIOUS consortium gathers partners from academia, SMEs and hospitals with comprehensive expertise in networking, pervasive sensing, cognitive analysis, nutrition research, semantic technologies and motivational techniques. We have chosen to focus on type II diabetes as a central use case, while our prototype will be easily adaptable also to other lifestyle induced diseases. The system will not only detect and communicate detailed early warning signs, but also provide forecasts of future developments and associated problems (if change recommendations are not followed). Extensive lab and field based user trials will demonstrate the efficacy of the PRECIOUS system and prove its positive and lasting impact on individual quality of life as well as public health sector development.