act on vs fulfill

act on

verb
  • To act decisively on the basis of information received or deduced. 

  • To affect something. 

  • Το act accordingly to a (usually sublimated) desire or impulse. 

  • To take action against something. 

fulfill

verb
  • To satisfy, carry out, bring to completion (an obligation, a requirement, etc.). 

  • To emotionally or artistically satisfy; to develop one's gifts to the fullest. 

  • To package, distribute, or ship goods. 

  • To obey, follow, comply with (a rule, requirement etc.). 

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