Did you know that the astronauts while in orbit, regularly engaged in sports simulators. In the first flight into space, it was not. And after a few months of being in zero gravity, they simply could not walk on the ground. Their muscles without experiencing physical stress, relax so much that they could not cope with the terrestrial attraction, just a few months. Since the human brain takes place about the same. In childhood and adolescence, when we master various sciences, the brain has to work actively. He has to remember tons of information, to differentiate it. When applying for a job in the first months of the brain is also active. He needed to put into practice all the knowledge to learn the algorithm of actions in the company. But when all the systems are debugged, the brain reduces its activity. The human body - is the energy-saving system. If he gets enough water, it starts to save the one that already exists, if not activated any body, he shuts it down, to have enough energy to something else. Therefore, the brain, like muscles, need constant training. And it's better than reading books regularly - could not come up with anything.