You may treat the past and future as realities, but they are only realities in your memory and imagination. Only the present exists.
We are terrified by this life because it is the only one we know we have, and it is dying from the moment it is birthed.
With each passing moment, an infinity of potentialities become just one reality, your life narrowing with each tick of the clock.
Perhaps the only thing we might legitimately lament in an old man’s death would be his failure to have used his time well.
Life is hard because it cannot last, because it must not last. Its very definition is that which lies tenuously between nonexistence and nonexistence.