"You'll find as you grow older that you weren't born such a great while ago after all. The time shortens up"

This quote by William Dean Howells is a tip that time passes rapidly which life is short. He is recommending that as we age, we recognize that we are not as far removed from our birth as we may have thought. He is emphasizing that life is fleeting and that we ought to make the most of it. He is likewise suggesting that we ought to not take our youth for approved, as it passes rapidly. He is motivating us to maximize our lives and to value the time we have. He is advising us that life is valuable which we need to make the most of it. He is suggesting that we need to not lose our time, but instead use it to maximize our lives. He is reminding us that life is short which we need to take advantage of it while we can.