spur on

Goad or urge ahead, as in The thought of winning a Pulitzer Prize spurred the reporter on. This expression transfers using spurs to make a horse go faster to incentives of other kinds. [Late 1500s]

The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.