pluck up vs undertake

pluck up

verb
  • To remove or acquire by plucking from, for example, the ground; to pick up. 

  • To become more cheerful. 

  • To summon positive emotion (especially courage); to muster. 

undertake

verb
  • To take upon oneself; to start, to embark on (a specific task etc.). 

  • To commit oneself (to an obligation, activity etc.). 

  • To pass a slower moving vehicle on the curbside rather than on the side closest to oncoming traffic. 

noun
  • The passing of slower traffic on the curbside rather than on the side closest to oncoming traffic. 

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