Energy is an integral part of everyday life, but people usually ignore its importance. Life lies in movement, and energy is its foundation. Life needs energy every day; just as a steam engine needs coal, an internal combustion engine needs gasoline, or an electromotor needs electricity, energy is the fuel of your body. Even if you do nothing, functions like breathing, heartbeat, blood flow, body temperature, and so on require energy. As long as you are alive, you need energy, for which you have to eat. Every mouthful of food you eat contributes to the continuity of your life. The more physical activities (work and exercise) you indulge in, the more energy you consume. When the energy you take in is more than what you consume, it will be stored in your body and become fat, which is like depositing your money in a bank. When the energy you require is less than what you consume, it will be taken out from the fat in your body for consumption, which is like spending your previous deposits.