How do you know when it's a reaction?

From: Eightfold Path 1

Student: How do you know when it's a reaction?

Ken: I think it's sometimes very difficult to tell. But one of the qualities--the couple of qualities--one is stickiness. You know, it isn't quite clean, it's like...and it's a little sticky. This is not a rational way, I'm describing a quality to it. And another way is insistence. Insistence: it has to be this way!

Whenever the internal vocabulary is: has to, must, always, never. Very, very good chance that there's a reaction, a reactive pattern operating. Well it just has to be this way!

I mean, one person I was reading recently says, "Belief is where we stop thinking." This is actually a pretty good indication of reaction. When you stop thinking and it just has to be that way, then you're in reaction. Because you've closed down, it's fixed. So insistence, fixedness, stickiness these are the qualities I use to recognize reactions. Does that help at all?