At the molecular and submolecular levels, life dances. It flows, swirls, pulses, gyrates, vibrates, thrusts, and orbits, an unceasing play of motion, an endless and untiring dance. Even a most solid and unmoving piece of rock, when viewed through an electron microscope, becomes a constellation of infinitely small and ephemeral particle/waves, spinning their way through large volumes of open space. Such microscopes reveal energy itself—pure vibration—the heart of manifest reality.
Human beings have found it healthy and empowering to support and expand this essential vibration, that it helps to “boil energy,” and that exciting energy to a higher rate of vibration feels good and improves life. How sensible then, and easy, to actually vibrate the physical body—to shake it, bounce it, spin it, and twirl it—to dance.
When we arouse, activate, and excite our vital energy to its fullest, then we feel fully empowered and capable of the extraordinary. When our energy remains dormant, cold, and tightly contracted, then we feel diminished and limited, and far more prone to failure and disappointment.
If a "big" healer wants to go into the fire, we would let him, because he is an owner of num [energy]. He may kneel and stick his head in the fire and hold it there. —Kung firedancer
Several times during the evening I get the group up and shaking. Nothing difficult, esoteric, or even prolonged—we just stand up and shake it out. Thirty seconds of such movement always leaves the group feeling lighter, freer, happier, and more optimistic.
So often that’s all we need do when we find ourselves contracting: feel the energy at a visceral level and cause it to boil by physically moving the body. Unfortunately, we too often do precisely the opposite when contracting: we sit still, stuck and unmoving, thinking and worrying, arguing with our fear, the energy becoming tighter and tighter.
When the num in their body is boiling and as hot as the fire, they cannot be burned when working with the fire. When their num is dormant or cold or cooled down, they can be burned. —Kung firedancer
When we love, we open ourselves to all of the benefits of excitement, while freeing ourselves of the varied aches and pains of contraction.

Unless otherwise noted, all text is from the book, Dancing With the Fire (Bear & Co, 1989), by Michael Sky.