This exercise is used too heat up your body in extremely cold temperature's and the heat can last for many hours. One man even set a world record using this techinue by laying in freezing cold water under 27 degree's for hours.
Inner Fire Yoga, or Tum-mo, is the basic method used in the advanced stage of most tantra systems. When doing this practice, we will need to visualize our body in a certain way. This is called the "Vajra Body" and incorporating it into our self-image provides a useful way to work with our bodily energies. The structures visualized are not actually there when the body is autopsied. There are correlates with our physical bodies, yet that is only part of the picture. When we close our eyes and feel our bodies, it is hard to deny that different parts of the body have different energies and feelings. In any case, to do the practices, one needs to suspend disbelief and visualize the postulated structures and energies. After extended practice, the visualizations become internalized and become powerful tools for calming ourselves, connecting with the body and channeling energy.
Rationale: As babies, we are born with blissful energy freely flowing throughout our entire body. As we develop, this energy is inhibited by the traumas of life and stored in our neuromuscular systems. We no longer breathe freely and our muscles become distorted with tension and stored psychic and physical pain. Inner Fire Yoga teaches us a method to free up this trapped energy and use it to our advantage.
Inner Fire Yoga as a Way to Redirect the Energy of Anger, Sexual Desire and Other Emotions: If we look carefully at emotion, we find that an emotion is actually a energized physical sensation in one part of the body or another. Thoughts are superimposed on these energies. The energy of emotion can scatter us, or we can learn to use it to center ourselves. In Inner Fire Yoga, energy is generated and collected in the navel chakra and spread upward through the center of our body, centering and energizing us in a positive way.
Sexual desire and anger can be very useful. Sexual energy in most adults is usually limited to the area of the sexual chakra. When this energy is spread throughout the body, it really isn't just sexual anymore. It is a total body energized or "blissful" feeling. This is not the ordinary limited bliss of orgasm. Sexual energy can be freed up and distributed throughout the body by moving it into the navel chakra and then doing the Inner Fire Yoga. Anger is energy also, but the energy can be harmful. In the inner fire yoga we can learn to take the energy of anger (usually felt in the solar plexus) and throw it also into the navel chakra as fuel.
Emptiness:
The "blissful" body is only half of the equation in Tantra. The other half is the indispensable understanding of non-dual awareness, or "emptiness" (the mind free or empty of conceptual divisions).
Chakras - Energy centers of the body that we postulate. Certain energy centers correlate with certain feelings (e.g., grief is felt in the heart).
Channels - Pathways that connect the energy centers. There are many, but we visualize three main ones. Our bodily energies flow along these pathways.
Drops - Little packages of consciousness/energy that flow through the channels. We postulate these, place our awareness on them and this stimulates energy in that area of the body. (Variously called drops, tigle, kundalini energy.)
Psychophysical knots - Areas of the body which are hardened or tense due to stored emotional or physical trauma. A knot is visualized as a crinkled or twisted channel in the area where it meets a chakra. Usually the heart chakra has the biggest knot problem.
Very Short Outline of Inner Fire Yoga:
1. Nine breathings (to settle the body and mind);
2. Picturing oneself as a hollow body;
3. The Six Hatha Yoga Exercises to free up the body's energy. See Mullin, Glenn, The Six Yogas of Naropa, Snow Lion Pub.
4. Visualization of the "Vajra Body" (illustrated above);
5. Generation of energy in the navel chakra;
6. Moving the energy up and down the central channel (in various ways) producing a total-body "bliss."
7. Application of the non-dual mind. This "bliss" produced by the above method is a bodily state of relaxed focused clear consciousness that is very conducive to the state of Non-dual Awareness emphasized in some lineages of Insight meditation, Dzogchen (where it is referred to as "Rigpa" or The Natural State"), Highest Yoga Tantra, (Where it is referred to as 'The Union of "Bliss and Emptiness," "Method and Wisdom," "Male and Female," or Mahamudra);
8.Use of mantra or sound. After we have attained this state of mind and body which is free of conceptualizing and thoughts, we can use mantra to "fill the vacuum" that is left and keep the old patterns from creeping back into consciousness. Always appropriate is the mantra of Shakyamuni Buddha
