quail vs run out of steam

quail

verb
  • To lose heart or courage; to be daunted or fearful. 

  • Of courage, faith, etc.: to slacken, to give way. 

  • To waste away; to fade, to wither. 

noun
  • The meat from this bird eaten as food. 

  • Any of various small game birds of the genera Coturnix, Anurophasis or Perdicula in the Old World family Phasianidae or of the New World family Odontophoridae. 

run out of steam

verb
  • To run out of energy or motivation. 

How often have the words quail and run out of steam occurred in a corpus of books? (source: Google Ngram Viewer )