Why do you always feel like you don't have enough mental energy? Because mental energy is not primarily a matter of willpower, but a problem with the energy system. When you don't get enough sleep, your focus, emotional stability, and ability to take action all decline; regular sleep restores your body’s rhythm and boosts energy and execution ability. Many people think that having strong mental energy allows them to go to bed early, but in reality, it's usually that they sleep well first, and then they have the mental energy to face life.