We are the only unfortunate (or fortunate, depending who you ask) animal that is aware of their limited time on Earth. That realization can lead to paralyzing fear and existential dread. And yes, some days one will feel as if nothing accomplished or wanted to accomplish is of any value at all, since it will all dissipate into the memory of the universe once our day comes, and we are gone.
But the fight must never stop. We cannot allow Death to take anything more than our lives.