do what you can

Hope isn't a choice, it's a moral obligation, a human obligation, an obligation to the cells in your body. Hope is a function of those cells, it's a bodily function the same as breathing and eating and sleeping. Hope is not naïve, hope grapples endlessly with despair. Real, vivid, powerful, thunderclap hope, like the soul, is at home in darkness, is divided; but lose your hope and you lose your soul, and you don't want to do that, trust me, even if you haven't got a soul, and who knows, you shouldn't be careless about it. Will the world end if you act? Who can say? Will you lose your soul, your democratic-citizen soul, if you don't act, if you don't organize? I guarantee it. And you will feel really embarrassed at your ten-year class reunion. People will point, I promise you; people always know when a person has lost his soul. And no one likes a zombie, even if, from time to time, people will date them.
The great Polish poet Czeslaw Milosz has a poem titled "On Angels"--you can imagine why I was drawn to it--and it concludes by articulating the best possible answer to What am I doing here and Why me. The poet is haunted by a voice:

I have heard that voice many a time when asleep
and, what is strange, I understood more or less
an order or an appeal in an unearthly tongue:

day draws near
another one
do what you can.

From Tony Kushner's commencement speech at Vassar College, May 26, 2002.