The performance of an activity can have positive incentives per se, and individuals may engage in an activity purely for the enjoyment of it. The engagement due to the enjoyment of an activity is often called intrinsic motivation. Besides this understanding of intrinsic motivation, other conceptions are presented (self-determination, experience of competence, interest and involvement, mean-end-correspondence, learning-goal orientation). In doing so, the problem became evident that the term intrinsic motivation refers to different, even conflicting conceptions. With the “Extended Cognitive Model of Motivation” different aspects of motivation are theoretically integrated. Instead of using the term intrinsic motivation, we use the term activity-related motivation. Qualitative and quantitative ways to measure activity-related incentives are outlined. Finally we present an intensively studied activity-related incentive, i.e., the experience of flow.