Staying healthy is a state of mind.  People are genuinely and almost always either positive or negative.   If you are negative then you will probably have been hurt at some point in time and not ever forgiven him or them who hurt you.  This will allow bitterness to set in and you will not be able to laugh easily and smile comfortably and even will cause your relationships to fail.  Often they will crumble around you and you will be bewildered as to why.  Bitterness is a terrible waste of time and energy.  Some people try to hide it and try to have good relationships but it will always be there smoldering a fire that won't go out and will destroy your peace of mind.  
Positive thinking on the other hand will free you to do great things.  Often desires are met and exceeded by people that are positive about who they are and what they are doing in life.  You have ultimate control over this process also.  You can choose to be one or the other in any given circumstance that you find yourself in.  Most people have no idea that they have a choice and much less that it is their right and obligation to choose.   
Well,  Just some notes here today to help you out and on your way!! Enjoy~~!!