When you want something that you cannot have, you must either change what you want or change what you have in order to avoid falling into despair over impossible possibilities.
But what if what you want is something that you should want? What if it's something that you need, even, in order to continue to progress in God's great plan of happiness? What then? You wanting it is supposed to be a good thing, but then it's something that you want but you still don't have, and you want and you still don't have, and you still don't have, and you still don't have and you start to wonder if maybe you should change what you want, because what you have sure isn't going to change anytime soon.
That is why I choose to not think about it at all, most of the time. And thankfully, the gospel is so big and vast that it is possible to ponder many of life's mysteries without contemplating what you want and do not have.
I could write pages more on this subject, but I don't want to. Thus this is the end.