Come onto your hands and knees. Make sure your knees are under your hips and your wrists are under your shoulders. Begin in a neutral spine position, with your back flat and your abs engaged.
Take a breath in, and as you exhale, round your spine up to the ceiling, pulling your abs toward your spine, and simultaneously tuck in your tailbone (don't clench your tush) and tuck your chin toward your chest.
As you inhale, let your belly soften, arch your back, and lift your head and tailbone. This part of the stretch is called cow.
Continue flowing back and forth from cat to cow, breathing deeply so as not to rush each movement.
Repeat for five deep breaths, which is about 30 seconds.