start a fire under (someone or something)(redirected from start a fire under them)
start a fire under (someone or something)
To motivate someone or something to take action. The deadline really started a fire under us—we never would have gotten all that work done otherwise. It's a shame that he got fired, but it might just start a fire under him to look for a job he really loves.
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.