For many, if not most, in our world, work is the place we look to for our identity.  This is the natural outcome of sin.  What was once meant to glorify God is now used to grab glory for ourselves.  But God in his grace comes down to rescue those who are trying to build their way up to him.  And when we pause to remember that he is God and we are not, there is a release from the tiring need to work for identity.