Passion is the heart of success. It is so rewarding that it is already satisfying, before, and even without, the finish line of success is reached. The central topic in this chapter is the distinction between obsessive and harmonious passion. Obsessive passion (e.g., pathological gambling, gaming, workaholism) allows no space for other activities and the person is no longer in control of it. Harmonious passion creates space for other activities, is consonant with them, and gives the feeling of control. A person with a harmonious passion for sports, art, music, or science is able to shift their energy to other passions (e.g., welfare work, eco-activities) or to other concerns that are felt as central in one’s life (e.g., love for one’s children, care for one’s parents, warm relationships with friends). In obsessive passion, one I-position dominates all other positions in the self. In harmonious passion one I-position receives full attention when being involved in the activity. However, the person has the flexibility to shift to another activity that requires one’s full engagement when the situation demands it. Given this openness and flexibility can harmonious passion function as a promoter position in the self. In this context, the concept of “grit” as a combination of passion and perseverance in reaching a long-term goal is analyzed and critically discussed. It leads to the conclusion that the combination of passion and perseverance has to be replaced by the combination of passion and flexibility.