Whenever I teach this in class, I relish the translation of its sanskrit name. Kapalabhati Pranayama means skull shining breath. It's enough to make you at least curious, right?
Done with precision and regularity, kapalabhati can be a highly beneficial cleansing technique to clear mucus, relieve congestion, improve lung capacity, and regulate health. You get so cleansed your skull shines. (FYI, skip it if you're pregnant, have high blood pressure/heart condition, or if you have undergone chemotherapy or radiation recently.)
Do it in the morning, and you'll feel more mentally clear and awake immediately.
Feeling tired? Get oxygenated feel more energized versus reaching for more coffee.
Overall sluggishness? The pumping and cleansing can help you feel lighter and let your digestion do its best work.
Cold and shivering? K-breath can build body heat, too.
How to Practice Kapalabhati
Sit comfortably in a way that allows your spine to be as long and tall as possible. You can sit on a cushion or chair, as long as you're not slumping (be honest about this and really set it up right).
Inhale through both nostrils all the way and exhale through your mouth for one round of preparatory breath. Close your lips.
Next inhale: Breathe in about halfway, then sharply pull your navel back toward your backside (as quickly as a snap) to exhale only out of your nose. The emphasis is on the exhale, which should be brief but active, while the inhale is a passive allowing of breath to re-enter the body.
Try to focus the action in the navel and keep shoulders as relaxed, but still, as possible.
Start with 15 and work your way up to a round of 30 or 100, eventually.
You might feel a little bit "high" afterward, and if so, take a few soothing breaths that are normal and stay fairly still and quiet for a bit. If not, proceed with your day and see happens with this renewed burst of cleansing, flowing breath and energy!