Come onto your hands and knees so your back is flat with your abs engaged. As you inhale, let your belly soften, arch your back, and lift your head and tailbone. This part of the stretch is called Cow.
With an exhale, round your spine up to the ceiling, pull your abs toward your spine, and simultaneously tuck your tailbone in, drawing your chin toward your chest. This part is called Cat.
For five breaths, continue flowing back and forth from Cat to Cow, breathing deeply so as not to rush each movement.