124 And how much weariness do we find that the short stages of our lives bring us! The boy longs to be a young man; the youth counts the years leading to riper age; the young man, unthankful for the advantage of his vigorous time of life, desires the honour of old age. And so to all there comes naturally the desire of change, because we are dissatisfied with that which we now are. And lastly, even the things we have desired are wearisome to us; and what we have wished to obtain, when we have obtained it, we dislike.
Source: On the Death of Satyrus (New Advent)