A few months ago someone in our church said something like, “I'm starting to wonder what God is preparing me for, I'm getting old.” Meaning that they don't feel they have accomplished a specific great work for God and they don't foresee that great work in their future.
Well, I think sometimes God does have a particular “great work” he is preparing us for, that he uses all other happenings in our life to prepare us for and causes all things to work together in such a way that we are “at the right place, at the right time” and have been prepared perfectly for just that situation, to accomplish that specific grand work.
But sometimes I think God “just” uses this life to prepare us for our life in Heaven, that in some lives there are no “great works” but just little, simple ones (in man's terms) that still have eternal significance, that still echo beyond time. And I think such a life is more than okay, for this life pales in significance, is a “mere breath” when compared to the Life that is to come. So all our preparation, even if it accomplishes nothing of grand significance while we are here, is no less important, indeed is even more important, than a preparation which prepares us for anything here, no matter how grand.