Why

Why is it that we are taught that if we get a favorable answer to what we pray or ask from God we immediately have to do something good in return or change something in ourselves, which in time will return to us after we forget the promise or thing that happened to make that change? Why can't we see and understand that God really loves us as we are, and that he hopes and wishes us to make the change, but that he doesn't force the change in us? That it has to come from within us to want that change?.....