It is very simple.
Everything is real.
Except for what you think.
So, if you think you see a particular situation as it is then this is a thought. So it is not that.
If a new thought occurs it is also not that.
Build an imaginary pile of these thoughts at your side (yes, another story) and continue until you have exhausted all your thoughts. As Sherlock Holmes said, “When you have eliminated everything that is impossible, what remains is the truth, however unlikely it seems.”
See what remains after you have exhausted all your thought possibilities.
If you know what this is, then it is also not that.
What is left?