Figuring out hard problems requires thinking. Indeed, one of the odd things I remember from elementary school was a lesson on the STAR method - stop and think before you act and then review. 

The method’s brilliance finally dawned on me yesterday. The key insight is not expressing the need to think as everyone knows that. The need to review is also fairly well understood.  

The key insight is the need to stop first. Stopping is a critical, fundamental skill for thinking. And, it’s a hard one that I’ve never heard talked about or thought about myself. 

Thinking, especially for the hard stuff, requires stopping.