This is an excerpt from Breathe, Focus, Excel by Harvey Martin.
This exercise creates fluidity in the breath as it matches the movement between two positions—cat and cow. Get onto all fours with your shoulders over your wrists and your hips over your knees. The first movement is the traditional cow position from yoga. Inhale through the nose as you curve your lower back and lower the belly, roll the shoulders back, and lift your gaze toward the sky (see figure a). The next movement is the traditional cat. Exhale through the nose and reverse your position by arching the back upward, pulling the belly in while pushing the rib cage up, and looking in toward the navel (see figure b). Repeat the movement as you inhale and exhale. Perform two sets of 10 breaths.