The randomization of the participating patients into three groups is necessary to evaluate the effectiveness of the InterWalk app. The intervention groups (group 2 and 3) are alike as long as the standard rehabilitation with physical activity proceeds in the municipality. From hereafter only group 3 will be supervised and will receive motivational support from the health professionals. This differentiation between groups is needed in order to obtain insight regarding motivational factors of importance to the individual, to maintain a physical active everyday life.