do one good
Be of benefit to one, as in I'm sure some fresh air will do her good. [Late 1400s]
Also, do one's heart good. Please, gratify, give satisfaction. For example, It does my heart good to see the young couple so happy.
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.