"Do not be daunted by the enormity of the world's grief.
Do justly, now. Love mercy, now. Walk humbly, now.
You are not obligated to complete the work, but neither are you free to abandon it."
(I saw this quote, based on the one from Micah, on social media and really liked it, but there seems to be some difficulty in finding its exact provenance. Perhaps that doesn't matter. The sentiment remains as valid whether or not we can figure out who said it first)