The Heart Center (also called the Ego Center or Will Center) is one of the 9 Centers in the Human Design BodyGraph and one of the 4 motor centers (alongside the Sacral Center, Solar Plexus Center, and Root Center). It is the only motor center connected to the Tribal circuit group, and it governs willpower, ego drive, self-worth, and the ability to make and keep commitments. When defined, the Heart Center provides consistent, reliable willpower and a stable sense of self-worth — these individuals have the capacity for consistent ego-driven effort and can make reliable promises. When undefined, willpower is inconsistent and variable, and the Not-Self pattern involves constantly trying to prove one's worth — leading to overcommitment and exhaustion. Only approximately 37% of the population has a defined Heart Center.