Identification, in the Gurdjieffian sense, is (and these are my own words):
“Falling asleep into your own opinions.”
Consider the degree to which we place things outside of ourselves within the construct of ego, the mechanical self.
If I play tennis, and someone criticizes tennis, I feel the emotional reaction as if someone criticized me, my own achievements, my self worth. The ego has absorbed the idea of tennis playing into itself as a persona.
This may seem benign, but think about how quickly one will feel slighted at criticisms of ideas, concepts, or events brought up in conversation. Things which one might not care about at all! But because you said them, you identify with them (unfortunately). You become what you say, and when a point is counterargued or rebuked, all of the sudden you feel as if “you” have been personally criticized.
It’s important to keep an eye on the process of identification. You are not your thoughts.