Muscles are special tissues that help us to move, lift, walk, climb stairs and even dance. Why even for smiling you have to use your face muscles. Muscles are attached to the bones and when a muscle shortens the bone moves causing the movement of that limb. There are even muscles that are present in your stomach and the intestine that help in the digestion of your food. Why, even your heart is nothing but just a bag of muscle that pumps your blood into the body So, next time when someone asks you- "What is the secret of your energy?", Just shorten your smiling muscles (smile) and say, "That is the secret of my energy!"