buck up vs take heart

buck up

verb
  • To become encouraged, reinvigorated, or cheerful; to summon one's courage or spirits; to pluck up courage. 

  • To pass on to higher authority for resolution. See also pass the buck. 

  • To encourage; to hearten. 

intj
  • Cheer up; take courage; take heart. 

take heart

verb
  • To be courageous; to regain one's courage. 

intj
  • Used when encouraging someone to bear or take up a difficult situation. 

How often have the words buck up and take heart occurred in a corpus of books? (source: Google Ngram Viewer )