A prompt I use probably twice a week, stealing it from nobody and giving it to everybody:
"I'm about to make this decision: [decision]. Here's my reasoning: [reasoning]. Steelman the opposite position. Then tell me which version of me — the one making this choice or the one making the opposite choice — sounds more like they're rationalizing vs. reasoning."
That last line is the unlock. Most "play devil's advocate" prompts give you a polite counterargument. This one makes the AI evaluate your thinking quality, not just your conclusion.
I've killed three bad ideas this quarter with it. I've also pushed through on two things I was about to chicken out of, because the AI called out that my "reasoning" was actually fear wearing a suit.
Try it on the next real decision you're sitting on. Report back.