Soul gives a man personality, self-awareness, rationality and natural feeling. The body is a complex physical creation by which a person relates to this world and to other people in the world. We now know that every person's body is in large measure a product of their DNA code which exists in every cell of the body to program its amazing development. As marvellous as the body may be, man has a non-physical aspect which consists of a different kind of materiality spirit. It is this part of man that is eternal.
Man is an intricate unity as well as being a three part being.
For this reason, whatever happens in one part of a man's being has repercussions in other areas as well. For example, it is well known that a healthy, fit body is conducive to an upbeat attitude in the soul. There are plenty of other examples that can be given of how all these aspects of man effect one another. It is a scientific fact. Obviously much valuable research could be done into the relationship between spirit, soul and body.