don't let the grass grow under one's feet

Act now, don't delay. For example, Write your applications today; don't let the grass grow under your feet. This expression alludes to waiting so long that grass can grow. [c. 1600]

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