Lie on your back. Still. Perfectly still. Your body doesn't/can't/mustn't move. Inhale. Exhale. Calmly. You're not moving, it's not you breathing. The air is pressing/squeezing/seeping into your lungs as if though it wanted to go there/had its own will/on its own accord. It probes/wanders/lingers, visits every crevice/rounded surface/wet warm spot of the walls of your lungs. You experience how the air inside of you is part of/not separate from/the same as the air surrounding you. You are wrapped in/filled with/merging with the air. When you exhale, it's not you exhaling, it' s the air growing tired/curious/satisfied, moving on to a new pair of lungs. Soon, very soon, new air, previously unknown to you, will fill you/examine you/experience you, just like the previous air. Only different. It's not you moving through the air, it's the air moving through you. Lie still. Lie perfectly still. Let the air breath you.
(Thanks BKS and CMIII)