乐天知命

樂天知命
lètiānzhīmìng
to be content with what one is

CEDICT

to be optimistic and content with life

Wiktionary

顺应天意的变化，固守本分、安于处境且悠然自得。语出《易经．繫辞上》：「乐天知命故不忧。」《儒林外史．第八回》：「近来我在林下，倒常教他做几首诗，吟咏性情，要他知道乐天知命的道理。」也作「乐天安命」、「知命乐天」。

重編國語辭典

Entry Composition

1 乐天 lètiān
  1. carefree
  2. happy-go-lucky
  3. optimistic
2 知命 zhīmìng
  1. (literary) to understand the Decree of Heaven; to know destiny
  2. (literary, idiomatic) age of fifty
  3. age of fifty
  4. to understand the Decree of Heaven; to know destiny