Have you ever felt tired after a day at school? That feeling you get from doing tasks that need a lot of attention and focus is called mental fatigue. Scientists created tasks in their laboratories to study this feeling. They observed that when we are mentally tired, both our thinking abilities and physical performance become worse. Scientists are not exactly sure why this happens, but mental fatigue can cause changes in the brain. One small brain region located in the front of the brain, called the anterior cingulate cortex, becomes less active when we are mentally tired. This can make us feel like we do not want to put as much effort into doing things, and that is why our performance declines. The good news is that scientists found ways to reduce mental fatigue. Paying attention to the present moment, listening to music, doing physical exercise, or having caffeine can make people feel better.