Lifestyle diseases like unspecific back pain affect a large percentage of the population, especially in the age group 55 and older. Physiotherapy exercises are often perceived as dull and boring and many patients are not motivated to perform them regularly. Exergames can motivate patients to perform their exercise through playing a game, however, designing motivating game elements that generalize well to a variety of exercises is challenging. We report on our development process, on how we employ human-centered design in order to create motivating exergames, and on how we developed the concept of Living backgrounds as the result of this design process.