The one that come to mind first is, "Life isn't fair", we all have to go through different situations, circumstances, and trials. That we must overcome.
Having patience truly is a virtue, because everything doesn't come to us or happens to us exactly when we want it to. The sooner we learn that we can not control everything the better off we'll be. Going back to the first comment on the thread, you can really only trust in one, completely with your heart, mind and soul and that one isn't man.