" Physical fitness is not only one of the most important keys to a healthy body, it is the basis of dynamic and creative intellectual activity. The relationship between the soundness of the body and the activties of the mind is subtle and complex. Much is not yet understood. But we do know what the Greeks knew: that intellignce and skill can only function at the peak of their capacity when the body is healthy and strong." ~ President John F. Kennedy
   
What this quote means that physical fitness is one important key of keeping healthy body. For example, maintaing a good weight give you more strength of learning and doing more physical activties.