We often think that the solid parts of the body are our primary experience of the body, and that breath is something secondary. Actually, it’s the other way around. The sensation of energy is primary.

"We have certain preconceived notions of how the breath comes into the body, what we have to do in order to bring it into the body, how the process of breathing relates to the different parts of the body, and then we breathe in line with that. And many times it’s a caricature of what’s actually going on. So we have to learn to look at the process in other ways. Consciously change the way you conceive of your breathing; see what happens. At the very least it’ll give you a good insight into the relationship between mental events and physical events. It’s not always the case that the mind is just reacting to its experiences. Sometimes it’s shaping its experiences, too. If we don’t get a sense of how we shape things, we never really get a chance to look into the mind.

For starters there’s the concept of the breath not as the air coming in and out of the lungs but the energy flow in the body. Some people have problems with this; others have no problems at all. But allow yourself to think in those ways and see what happens. And instead of thinking of the body pulling the breath in, remember that your primary experience of the body is breath, an energy flow. Our perceptions tend to solidify that, and so we often think that the solid parts of the body are our primary experience of the body, and that breath is something secondary. Actually, it’s the other way around. The sensation of energy is primary. So allow yourself to think in that other-way-around. Your sense of the solid body is sitting here in the breath, in the process of breathing. Whatever you perceive as an immediate, primary experience of “body,” think of it as breath.

If you’re having trouble with the breathing, if your breath seems constricted or tight, remind yourself of this, and it’ll open up a lot."

~ Thanissaro Bhikkhu "De-thinking"