It is a growing process from being young and brave to being indifferent to things.
The general meaning of this sentence is to tell us that inner growth is the real maturity, and the wave of longing for fate is understandable. It is a kind of courage to face difficulties, even a bit like the momentum that makes the storm more violent. But later, we gradually realized that even after the ups and downs of the world, we should take it lightly and turn the external vitality into internal and external calmness.