Fear
Anything that is about you. It shows up as ego, belief and expectation — and any negative feeling is a receipt for one.
My Big TOE defines fear as the opposite of love and, precisely, as being about self. It says fear is creatively expressed as ego, belief and expectation, and that it speaks in a recognisable register: I need, I want, I believe, I expect, I deserve.
The material identifies five roots that most individual fears trace back to — not being good enough, pain, the unknown, not being in control, and death or annihilation. It also warns that fears are hard to detect precisely because ego and belief are so good at covering them up.
In an interview, Campbell gives the practical instruction directly: if you feel anxiety, hurt, anger, insignificance — any negative feeling at all — that is ego, and the ego is there because of a fear. Trace it back. Ask what causes me to feel angry, to be upset. You will find a fear underneath.
Where this gets misread
That you have no fears, or only obvious ones. The claim is that fear is usually invisible from the inside, and that the reliable way in is not introspection about fear but noticing the negative feelings it produces.