“Physical fitness is not only one of the most important keys to a healthy body, it is the basis of dynamic and creative intellectually activity. The relationship between the soundness of the body and the activities of the mind is subtle and complex. Much is not yet understood. But we know what the Greeks knew: that intelligence and skill can only function at the peek of their capacity when the body is healthy and strong. “

In my opinion I think this quote is saying that physical fitness doesn’t only mean a healthy body it also means a creative intellectually activity . In other words if you have a body that is healthy and strong you may have good skills to do or what your good at.  

President John F. Kennedy ~