encourage vs motivate

encourage

verb
  • To mentally support; to motivate, give courage, hope or spirit. 

  • To spur on, strongly recommend. 

  • To foster, give help or patronage 

motivate

verb
  • To provide someone with an incentive to do something; to encourage. 

  • To animate; to propel; to cause to take action 

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