Staying focused means to stay centered on the Self. This makes the mind one-pointed, and when this happens the mind seems to disappear. On the other hand, the mind becomes a big problem when we are self-centered.
Being self-centered means the mind is preoccupied with ego, the small self. The small self, ego, is the identification of consciousness with the body and mind, and by extension, with other people, places, and things associated with the body and mind.
The identification of consciousness with the mind (and through the mind, with the body) occurs naturally. For example, when we are born we naturally begin to identify with our body and mind due to our association with them. However, it is unnatural to remain limited by our ego—in other words, it is unnatural to accept being bound by our ego (our identification with the mind, body and their various relationships and interrelationships). On the contrary, it is our true nature to be free and imageless, and if we are bound and caught up in our images it is our nature to break free.
Breaking free means breaking our images (including, especially, our self-image). When our images are broken our ego collapses—it cannot stand without the crutches of images. Hence, we need to remove our images and the only way to remove them is through the acquisition and application of Wisdom.