duh

As long as our happiness is tied to the things we can lose, we are vulnerable. This truth is core to the human condition and to understanding what God is doing in our lives. We really believe that God's primary reason for being is to provide us with happiness, give us a good life....We see God as a means to an end rather than the end itself. God as the assistant to our life versus God as our life....And so we are surprised by the course of events. It's not that God doesn't want us to be happy. He does. It's just that He knows that until we are holy, and we are fully His, we cannot really be happy. Until God has become our all, and we are fully His, we will continue to make idols of the good things He gives us...We are so committed to arranging for a happy little life that God has to thwart us to bring us back to Himself. It's kind of a regular purging I suppose.

~Walking with God
(thanks to Liz K.)