do (one) a/the world of good
To have a very positive effect on someone or something. If you're feeling sad, getting out in the sunlight should do you a world of good.
do somebody/something a ˈpower/ˈworld of good
(old-fashioned) do somebody/something a lot of good; benefit somebody/something: She’s under a lot of stress at work, and a few days at the coast would do her a power of good.