Your body is like a superbly engineered luxury automobile; if you don't use it wisely and maintain it properly, it will eventually break down, most likely in a bad neighborhood. To understand why this is, let's take a look inside this fascinating "machine" called the 'human body'.
The body is made up of billions and billions of tiny cells, which are so small that you cannot see them. The only people who can see them are white-coated geeks called "biologists". And they tell us that the human body consists of billions of these tiny cells, which combine to form organs such as the heart, the kidney, the eyeball, the funny bone, the clavichord, the pustule, and the hernia, which in turn combine to form the body, which in turn combine with other bodies to form the squadron. The various fitness-related organs are: 

THE SKIN Your skin performs several vital functions. For example, it keeps people from seeing the inside of your body, which is repulsive, and it prevents your organs from falling out onto the ground, where careless pedestrians might step on them. Also, without skin, your body would have no place to form large facial zits on the morning before your wedding. But for fitness-oriented persons like yourself, the important thing about skin is that it acts as your Body's Cooling System. Whenever you exercise or get on an elevator, sweat oozes out of millions of tiny skin holes so it can evaporate and cool the area. Unfortunately, virtually all of these holes are located in your armpits, which is stupid. I mean, you hardly ever hear people complaining about having hot armpits. So what we seem to have here is one of those cases where Mother Nature really screwed up, like when she developed the concept of nasal hair.

THE MUSCLES SYSTEM Your muscles are what enable you to perform all of your basic movements, such as bowling, sniping, pandering, carping, and contacting your attorney. Basically, there are two kinds of muscle tissue: the kind that people in advertisements for fitness centers have, which forms units that look like sleek and powerful pythons writhing just beneath the surface of the skin, and the kind you have, which looks more like deceased baby rabbits. The beauty of muscle tissue, however, is that it responds to exercise. Using modern exercise equipment such as the Nautilus machine, you can stretch those pudgy little muscle tissues of yours to the point where you won't even be able to scream for help without the aid of powerful painkilling drugs.

THE SKELETAL SYSTEM How many bones do you think your skeletal system has? Would you say 50? 150? 250? 300? More than 300? If you guessed 50, you're WRONG. There would be around 250, but its not all that important. The only important part of your skeleton, for fitness purposes, is your knees. Knees are God's way of telling mankind that He doesn't want us to do anaything really strenuous. When we do, our knees punish us by becoming injured, as you know if you've ever watched professional football on television: COMMENTATOR: Looks like a knee injury, from the way that bone there is sticking out of his knee.

THE DIGESTIVE SYSTEM Your digestive system is your body's Fun House, whereby food goes on a long, dark, scary ride, taking all kinds of unexpected twists and turns, being attacked by vicious secretions along the way, and not knowing until the last minute whether it will be turned into a useful body part or ejected into the Dark Hole by Mister Sphincter. You must be careful about what you eat, unless you want your body making heart valves out of things like bean dip

THE CENTRAL NERVOUS SYSTEM The Central Nervous system is your body's Messenger, always letting your brain know what's going on elsewhere in your body. "Your nose itches" it tells your brain. Or, "Your foot is falling asleep!" Or, "You're hungry!!!" All day long, your brain hears messages like these, thousands of them, hour after hour, until finally it deliberately rests your hand on a red-hot stove just for the pleasure of hearing your nervous system scream in pain

THE RESPIRATORY SYSTEM Your respiratory system takes in oxygen and gives off carbon monoxide, a deadly gas, by a process called "photosynthesis." This takes place in your lungs, yam-shaped organs in your chest containing millions of tiny little air sacs, called "Bernice." In a normal person, these sacs are healthy and pink, whereas in smokers they have the wretched, soot-stained, anguished look of the people fleeing Atlanta in 'Gone with the Wind'. This has led many noted medical researchers to conclude that smoking is unhealthy, but we must weigh this against the fact that most of the people in cigarette advertisements are generally horse-riding, helicopter-flying hunks of major-league manhood, whereas your noted medical researchers tend to be pasty little wimps of the variety that you routinely held upside down over the toilet in junior high school.

THE CIRCULATORY SYSTEM This is, of course, your heart, a fist-sized muscle in your chest with a two-inch-thick layer of greasy fat clinging to it consisting of every Milky Way you ever ate. Your heart's job is to pump your blood, which appears to be nothing more than a red liquid but which, according to biologists (this should come as no surprise), is actually teeming with millions of organisms, some of them with tentacles so they can teem more efficiently. The only organisms that actually belong in your blood are the red cells and the white cells. The red cells are your body's Room Service, carrying tiny particles of food and oxygen to the other organs, which snork them up without so much as a "thank you." The only reward the red cells get is iron in the form of prunes, which the other cells don't want anyway. If you don't eat enough prunes, your red cells get tired-a condition doctors call "tired blood" -and you have to lie down and watch "All My Children." The white cells are your body's House Detectives. Most of the time they lounge around the bloodstream, telling jokes and forming the occasional cyst. But they swing into action the instant your body is invaded by one of the many enemy organisms that can get into your bloodstream, these being bacteria, viruses, rotifers, conifers, parameciums, cholesterol, tiny little lockjaw germs that dwell on the ends of all sharp objects, antacids, riboflavin, and the plague. As soon as the white cells spot one of these, they drop whatever they're doing and pursue it on a wild and often hilarious chase through your various organs, which sometimes results in damage to innocent tissue. Eventually they catch the invader and tie its tentacles behind its back with antibodies which are the body's Handcuffs, and deport it via the bowel.