agitate vs muster up

agitate

verb
  • To disturb or excite; to perturb or stir up (a person). 

  • To cause to move with a violent, irregular action; to shake. 

muster up

verb
  • Look within oneself to summon a particular positive quality, such as strength, energy or courage. 

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