The human body is an amazingly complex system of bones, joints, muscles, and nerves, designed to work together to accomplish one thing: motion. Remember that motion is life. Everything about the human body is designed with motion in mind: nerve fibers stimulate the muscles to contract, muscles contract to move the bones, bones move around joints, and the nerve system controls it all.
As a matter of fact, research has shown that motion is so critical to our body's health that a lack of motion has a detrimental effect on everything from digestion to our emotional state, immune function, our ability to concentrate, how well we sleep and even to how long we live. If your lifestyle does not include enough motion, your body cannot function efficiently. First, you will not be as physically healthy and will suffer from a wide variety of physical ailments, ranging from headaches to high blood pressure. Second, you will not be as productive in your life because of reduced energy levels and the lack of ability to mentally focus. Third, because you have less energy, your activity level will tend to drop off even further over time, creating a downward spiral of reduced energy and less activity until you get to a point where even the demands of a sedentary job leave you physically exhausted at the end of the day.