Combination and Separation of Body & Soul !!!

Human souls are immortal,not a bit of doubt about it,but matter of the fact is that bodies they use to live in for some time ultimately perish and vanish.When we say the combination of body and soul do always give life to a human being and ultimately their separation do make them a "deleted folder", of course for an invisible "recycle bin". Now the question is that do we really believe in all this,if yes,then why don't we make adequate preparations for the day,the day of separation for our body and soul ?