You must be aware continuously

Discover all you are not. Body, feelings, thoughts, ideas, time, space, being and not-being, this or that - nothing concrete or abstract you can point out to is you.

A mere verbal statement will not do - you may repeat a formula endlessly without any result whatsoever. You must watch yourself continuously - particularly your mind - moment by moment, missing nothing. This witnessing is essential for the separation of the self from the not-self.