Only those touched by awe can appreciate just how small they are, how little the petty squabbles and annoyances that so consume the majority of humanity actually matter.
If you have risked death knowingly, or seen the unbridled fury of nature, or witnessed a supreme act of sacrifice, or loved fiercely and briefly; then you understand.
There is only death at the end. We are in this world for the briefest of moments, a mere glimmer of time; and after we are gone, we may be remembered for a day or a decade or a century. But eventually, all is forgotten. Time erases everything.
Do not be saddened. It is not hopeless, it is glorious, to live with the knowledge of your own mortality. You will breathe deeper, think clearer, and carry your head high.
All that matters is what we do today. The world is big and bad and beautiful and it should be no other way.