I am not anything that I can observe outside my body.
Have you heard of the Illusion of Separation? It's the notion that things that appear separated are, in fact, not separate at all.
Some spiritual teachers seem to want you to accept this very counterintuitive idea at face value, as sort of the price for entering nirvana. Once you give up this idea of separation, they seem to say, you'll begin to experience a deep, pervasive peace in your life.
It sounds tempting. Only, how exactly am I to undo the observable fact that, say, my cell phone and I are separate entities? How long to I have to meditate, exactly, to "see" that we're both the same thing?
To me, that seems a pretty heavy lift, at least without a few tools to help.
So instead, I’ll walk us in entirely the opposite direction: I believe that on the quest to answer the question Who am I?, it's far more helpful to assume that what you observe as separate is, in all likelihood, really separate. That is:
I'm here and it's there,
So it is separate from me.
Thus, it isn't me.
The strategy here is to answer the question Who am I? by peeling away layers of Who I'm not. And the first layer is the easiest: Clearly, I'm not any of the things around me that appear separate from me as inanimate objects, living things, or other people in the world.
So, if you're ready to agree, at least provisionally, that you are not any of the things that you observe around you – such as your phone, your dog, your best friend, or the moon – go ahead and jump to Insight 6.