brainwash vs toughen up

brainwash

verb
  • To affect one's mind by using extreme mental pressure or any other mind-affecting process. (e.g. hypnosis) 

  • To persuade completely and forcibly. 

noun
  • A distorting effect upon one's memory, belief, or ideas, as by propaganda. 

toughen up

verb
  • To make or become mentally tougher. 

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