For many people, the image of the breath energy in the body is a very strange or exotic notion, but actually it’s something very directly present to your awareness: your sense of the body as you feel it from within.

"The other set of problems has to do with your image of the breath energy in the body. For many people, this is a very strange or exotic notion, but actually it’s something very directly present to your awareness: your sense of the body as you feel it from within. It’s simply a matter of interpreting what you already feel in a different way. If you were to hold out your arm, the sensations that tell you that you have an arm there could be interpreted as perceptions of solidity or as perceptions of breath energy. The choice is yours. The sensations are the same, but the perceptions — and what you can do with the sensations based on the perception — will be different. The advantage of seeing the sensations as energy is that you can do things with energy that you cannot do with solidity. For example, if there’s a spot in your back that you think of as solid, you will simply leave it as solid. However, if you perceive it as energy and you realize that the energy is blocked, then you can do something about it. You can relax it or open it up to release it, and this allows the breath to become more comfortable. Your posture can improve and you can sit comfortably for longer periods of time.

It’s like those old magic eye pictures that were popular 25 years ago. If you look at them one way, they’re two-dimensional patterns. If you change your brain and look at them another way, you’ll see them as a different pattern entirely. What was two-dimensional now becomes three-dimensional. Now with those images, it was simply a perceptual trick with no practical consequences. But with the body, you can actually give yourself an advantage, depending on how you perceive the sensations. Once you become sensitive to these sensations as energy, then the breathing will become easier. Instead of thinking that you have to force the energy through a solid, you simply think of one energy flowing into and mingling with another, and in that way, good energy can penetrate deeper into the body. That makes it easier to be aware of the whole body breathing in, the whole body breathing out, with a sense of well-being."

~ Thanissaro Bhikkhu "Issues with the Breath"