help oneself vs work in

help oneself

verb
  • Used other than figuratively or idiomatically: see help. 

  • To serve oneself, especially to take food or other supplies, rather than wait to be served by another; used to indicate friendly permission or invitation. 

  • To exhibit self-control. 

  • To take something freely; to serve oneself without restraint. 

work in

verb
  • Used other than figuratively or idiomatically: see work, in. 

  • To find time or space for, amid other things. 

  • To work out using a machine in between the sets of someone who is already using that machine. 

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