Once a habit has been established, however, it’s important to continue to advance in small ways. These little improvements and new challenges keep you engaged. And if you hit the Goldilocks Zone just right, you can achieve a flow state.* A flow state is the experience of being “in the zone” and fully immersed in an activity. Scientists have tried to quantify this feeling. They found that to achieve a state of flow, a task must be roughly 4 percent beyond your current ability. In real life it’s typically not feasible to quantify the difficulty of an action in this way, but the core idea of the Goldilocks Rule remains: working on challenges of just manageable difficulty—something on the perimeter of your ability— seems crucial for maintaining motivation.