This exercise is adapted from one I learned from Nancy Houfek.
Begin on hands and knees, with the knees under the hips and the hands under the shoulders.
Allow the spine to drape downward, releasing the belly to maximize the distance between the sternum and pubic bone. Soften between the shoulder blades.
On an exhalation, draw the belly upward toward the spine without moving the back. Keep the outer abdominal muscles lengthened and disengaged, moving from the deeper transverse layer. On each inhalation, release the belly fully.
Imagine that you have an object in your navel, and on each inhalation, you drop it suddenly. Then, on the exhalation, you use your navel to pick it up once more. Perhaps dropping the object is a surprise, and you can allow your breath to drop in suddenly on a light gasp! Make sure your back continues to drape. The exhalation should not cause your back to arch.
After a few practice rounds, introduce the image of a birthday cupcake resting on the floor between your hands. There’s a trick candle in it that relights each time it’s blown out. Fully releasing the belly on each inhalation, use you exhalation to blow out the candle with one puff of air… with two puffs… three… four…. three… two… one… one… one… perhaps one long stream?
Sit back on your heels, maintaining the arched shape of your back body. Practice the mechanics of this breath pattern here: the belly releases for the inhalation and the ribs swing up, then the deep transverse abdominal muscle engages and the ribs float gently down.
Take a few moments at the end of the exercise to reset your spine to neutral and feel your breath at rest, sensing any shift in your awareness of breath movement. Try to take this awareness with you into the next thing you do.