put one's back into

/P UH1 T W AH0 N EH0 S B AE0 K IH0 N T UW0/
verb
  1. 1

    To make a strenuous effort to do something.

    โ€œWhen he puts his back into the work, he gets quite a lot done.โ€

Source: https://en.wiktionary.org/wiki/put%20one's%20back%20into