Exhortation: “You Are Not the Body, You Are Not the Mind!” lies at the very foundations of spiritual teachings originating from the Advaita masters such as Sri Nisargadatta Maharaj.
Yet for most of us, the mind and the body are all we have. At the same time, we have virtually no power over either of them. You’d expect some degree of control over that that you have, wouldn’t you? No, I’m not talking about some mind control tricks, or body care rules and rituals. They merely give you an illusion of being their master.
Now, let’s approach both parts of the “apparatus” that makes us humans, separately.

1. The mind cannot be depended upon. It tricked you so many times in the past… It led you astray and away from the safe path, and even right now, given the opportunity, will direct you to do the things that later you’ll regret doing. Actually, what makes the mind? Nothing more than a conglomerate of memories and concepts that you’ve acquired through your life experiences. But don’t ever rely on them!
For how you interpret reality is totally unique; yes, the word idiosyncrasy comes to mind…
Did it ever happen to you that you have had very different recollections of the same past moments, than your closest friend, partner or a family member? What makes for fond memories for you, for others invokes the feelings of resentment, fear, or indifference.
That’s why the memories are worthless. Never build your future on the past!

2. You body cannot be “you.” The “you” that sees the body and recognises its presence is the real “you.” This should be clearly grasped – an object cannot see itself. Your body can only be perceived by the “identity” that is independent (“outside”) of it, Noumenon. “But what about a mirror?” you may ask. Well, what you see in the mirror is not a “you.” It is just a reflection, a more-less accurate representation of your body… save for the distortions when the surface is crooked. Surely, you don’t want to rely on such a flimsy assurance as to your existing or not, do you?

It is your awareness that perceives the body and the mind as two separate identities. Appearing real, they originate from the same substance that the world is made off – consciousness. Yet they both are the consciousness and not the other way around. It is not the body that is consciousness; it is the consciousness that assumes innumerable forms, and your head, legs, hands – the body in its totality, is one of them.
Said Nisargadatta Maharaj: “When one talks of consciousness, one is likely to think in terms of an individual. But understand that it is not really the individual that has consciousness, but it is the consciousness that assumes innumerable forms. I keep repeating that the average person will not understand this. Why? Because it is too simple! To grasp, one wants something, some form, some shape.”

The essence of spiritual work is to deliver the liberation (from the body and the mind identity). That’s why unless you put into practice Maharaj’s words: “Think that, this (body and mind) is mine, but I am not that. I witness it as mine, but I am not that.” you’ll get nowhere. Yes, you are just only one or two illusions away from realizing That, which you have always been from the first!