As the rates of lifestyle diseases such as obesity, diabetes, and heart disease continue to rise, the development of effective tools that can help people adopt and sustain healthier habits is becoming ever more important. Mobile computing holds great promise for providing effective support for helping people manage their health in everyday life. Yet, for this promise to be realized, mobile wellness systems need to be well designed, not only in terms of how they implement specific behavior-change techniques but also, among other factors, in terms of how much burden they put on the user, how...