fire under

a fire under (someone)

The motivation to take action. Typically used in the phrase like "light/start a fire under (someone)." The deadline really lit a fire under us—we never would have gotten all that work done otherwise. Something must have lit a fire under Jenna—she has really started taking her schoolwork seriously. 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.

See also: fire

Farlex Dictionary of Idioms. © 2022 Farlex, Inc, all rights reserved.

*fire under someone

Fig. something that makes someone start doing something. (*Typically: build ~; light ~; start ~.) The teacher built a fire under the students, and they really started working. You had better light a fire under your staff. Either that or we will lay off some of them.

See also: fire

McGraw-Hill Dictionary of American Idioms and Phrasal Verbs. © 2002 by The McGraw-Hill Companies, Inc.