We find ourselves here, in these human bodies, living a human life. We are identified with our bodies because all we remember, generally, is this one experience. It's like when you are asleep at night, dreaming, you are only aware of that one dream. You're deeply focused within the one experience.
Think of your mind as being a radio with two stations. There is the chatty, discursive human mind, and then there's something else—a spacious, silent, totally nonjudgmental awareness of the whole situation. In ACIM terms, these two aspects are called the ego and the Holy Spirit. Sometimes they are referred to as the false self and the true self.
We are told that the false self does not exist, and yet it's a wildly untamed, meddling, grasping, rejecting pain in the ass. Also—it never shuts up. It wants, it competes and it creates problems that don't exist in order to get you to run around trying to solve them.
This ego is the mind of the body. Or rather it's the mind caused by identification with the body and its trials and tribulations. It's similar to playing a video game and identifying with your character, or your avatar, except it's a much deeper, more realistic game.
So there's You, with a capital Y, our silent, luminous, shared Self, and there's the body, and then there's the combination of You and the body-mind, which creates the self we know as "me."
"Me" is in a whole mess of trouble, because "me," believing itself to be this body, feels terribly endangered. And me IS endangered, because me is temporary. Me is a cloud, a thoughtform, a magic spell, a figure in a dream. And yet, wonderfully, quixotically enough, it is here to be experienced.
The important thing is that if you are suffering because of this experience of me-ness, you understand how to shift your attention to lessen the pain, should you be inclined to do so. You need to be able to find the dial and shift to the other station. This is mindfulness. That's all. It's like receiving a code that gets you to another level in a video game so you can avoid having to play your way through all the lives, deaths and rebirths.
There are many different codes to help you do this. Here's one: You are not your body. You are an eternal, shining being with no negativity whatsoever. This is a very real-seeming dream and the underlying emotion here is fear. Yet even here within this odd virtual reality, what is beautiful and what shines is because of You. All the beauty and love and light is You, shining through.
Here's another: Forgive. Stop resisting and judging what is. Let it go. This is perhaps one of the most magical codes of all because it completely disengages the "me" mind. The me-mind cannot exist without the idea of opposition to the here and now. It is completely suspicious of contentment.