Then I realized that it is good and proper for a man to eat and drink, and to find satisfaction in his toilsome labor under the sun during the few days of life God has given him—for this is his lot. Ecclesiastes 5:18 (NIV)
It's always hard to know which verses in Ecclesiastes to embrace wholeheartedly and which to scrutinize more critically as the logical conclusions of life without eternity in view.
I think this passage qualifies as both. Ecclesiastes is saturated with wisdom, exposing the folly of reveling in this world in ignorance of the end that is sure to come. Very few lights of hope glimmer on the surface of this book of poetry, but this verse appears to be one of them. To enjoy life and be satisfied in what you do . . . that is good and proper. But it isn't all there is.
Don't just live for today. Don't just live this day as though it could be your last. Live this day as though it were meant for life beyond the sun. Live this day for eternity as though it is one building block in the kingdom of Christ. That is your lot.