I don't remember who mentioned who first mentioned it on the SA forum but ever since I saw it, I have been repeating it to myself whenever the latest difficult child crisis hits.
It was me. I had a friend who told me that saying originally because I have an impossible ADD boss. I really struggle with his crap as a successful businessman at 66 years old. It hit me in the face one day that I need to also apply it to my adult difficult child son who is NOT a successful businessman (sigh...).