A Voice from the Past - Lewis

Any moralist will tell you that the personal triumph of an athlete or of a girl at a ball is transitory: the point is to remember that an empire or a civilization is also transitory. All achievements and triumphs, in so far as they are merely this-worldly achievements and triumphs, will come to nothing in the end.

C. S. Lewis, 1808-1963, The World's Last Night, The World's Last Night and Other Essays. (Harcourt Brace Jovanovich, 1960. p. 110)

How should this affect how we look at the world? How should it affect how we live our lives?