Just what the doctor ordered
Definition 1 of 1
Pro Tip 1/3Situational Use
Used when something is perfectly suited to one's immediate needs or problems. 
I was so hungry, and the pizza arrived just what the doctor ordered.
Pro Tip 2/3Expressing Relief
Commonly used to express relief after receiving something beneficial or soothing. 
A day off after the busy season was just what the doctor ordered.
Pro Tip 3/3Not Literal
The phrase is not medical advice but a figure of speech implying something beneficial. 
That joke was just what the doctor ordered to lighten the mood.