If we want to stay healthy(in any and every conceivable manner possible(?)), first thing we need is to know our body. What do we mean by knowing our body? Body is the epicentre of every activity we do throughout our lives or every thought we ever think in our life time. We are either able to connect or not but every bit of our act or thought returns by one medium or other in one form or other to our physical form of presentation known as body.
I am want to be a 100 meter sprinter. When I compare my physical abilities as an sprinter with standard abilities for a successful sprinter. I can reach to conclusions such as either I can be a 100 meter sprinter or 200 meter sprinter or a 400 meter. May be I can't be a sprinter at all. May be I can probably be a long distance runner. But in order to find out whether I can be a sprinter or a long distance runner or not being a sprinter/runner at all, I have to go through all the test to find this out. Some times this whole experiment or process may take a very long time. This results in the loss of most valuable commodity known as time besides some other noticeable losses which are equally capable of impacting us throughout our life time.
A question comes in picture whether it is possible to determine if a person can be something distinct(or what he/she dreams for) in his/her life time. If this can be determined before hand than we can save millions of people from doing something they should not do. And if this can also be established as well what a person should do before hand, it is possible to help that person divert all his/her efforts and available resources to achieve the primary objective of that facet or part of his life.
What we can conclude out of the above discussion is to determine on where our body stands in terms of different parameters for different established aspects of successes in the life time. These set of parameters represents basic qualities required to find out how fit a person is to do something. If we think about it deeply, we shall find that this is what every visible and invisible object is trying to achieve throughout its existence. Now the parameters for different established aspects of successes and our bodies' standing on these set of parameters can be categorized as healthy or not healthy for something. In general approach if we say somebody is healthy, we think that the person in question is physically in good health. We don't consider other kinds of healths which plays an equally important role in our life. For example a person is good in studies but not good when it comes to doing a job. Or a person shows a lot of strength while wrestling with someone but fails to replicate it when it comes to running a long distance race. We can find any number of examples for any facet of identified or established way of life.