fire in the belly vs zeal

fire in the belly

noun
  • The emotional stamina and vigor, passion, or inner drive to achieve something, to take action, etc. 

zeal

noun
  • The fervour or tireless devotion for a person, cause, or ideal and determination in its furtherance; diligent enthusiasm; powerful interest. 

  • The collective noun for a group of zebras. 

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