The Great Eastern Insight is what I term a common idea for most or all eastern religions.
Basically: The "self" is a self-constructed illusion...and attachment to this illusion is the source of most of your unhappiness. It's important to also keep in mind that they've (without ever saying this) incorporated the habit theory of practice as well.
This is not to say that you should (or can) abandon the habits you've created. Just that the conscious attachment to protecting the self is the problem.
"I'm not the kind of person who" is the sentence that is the cause of all your unhappiness.
Doing X because it's habitual, on the other hand, is a good thing, provided you've got good habits.
Indeed...it's worth thinking about that one might be able to consider a person to be primarily two-faceted. Un/sub-conscious habits of behavior/reaction, and conscious behaviors one takes in order to protect the self. If one can build good habits of mind, then the "self" truly is the enemy.