幼稚的我只会笑成熟的我只会哭
[yòu zhì de wŏ zhĭ huì xiào chéng shú de wŏ zhĭ huì kū]
Reflects on personal growth over time. It indicates that a younger version of oneself would easily laugh off troubles while a more mature one faces hardships with a more somber reaction, like crying, due to understanding things deeply.