least resistance, line of - Phrases/Idioms
The American Heritage® Dictionary of Idioms by Christine Ammer. Copyright © 2003, 1997 by The Christine Ammer 1992 Trust. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Also, path of least resistance. The easiest method, way, or course of action. For example, He tends to do what most people seem to want, taking the line of least resistance. This term employs resistance in the sense of “the physical opposition of one thing or force to another,” a usage dating from the early 1600s. It has been used figuratively since about 1900.