Inhale fully (100%) for 35-55 sequential breaths. When you exhale, just release naturally (don't push the air out all the way out). The idea is to create friction within your core, like a bellows blowing a flame in your sacrum. You may feel dizzy or experience muscle contractions in your mouth and hands. You may feel tingles. It's all O.K. Witness the energy bursting through your body like a dragon. Witness the sensations in your body. As you breathe, try to keep your shoulders relaxed while stretching your chest and upper belly muscles.
With practice, you can eventually make the breath circular:
People with vaginas: Imagine the breath entering through your cunt with passionate sweetness as you flex your perineum, locking the passion into your inner fire and adding to the friction... then imagine the breath exiting out through your heart in a passionate release.
People with penises: Imagine the breath entering through your heart with passionate sweetness as you flex your perineum, locking the passion into your inner fire and adding to the friction... then imagine the breath exiting out through your cock in a passionate release.
2. WITNESS THE VOID
After you last "quick breath," exhale naturally and just wait, without inhaling. Witness. Don't force it, just relax all your muscles. Witness the void of your body without inhaling. You might explore timing yourself to see how long it takes before your next necessary inhale. Recording retention times gives you a map of your progress. You'll find, with practice, your retention times effortlessly get longer and longer. The wisdom of Shunyata (emptiness) is called into the hollow space of breathlessness as you simply witness.
Alternative Brahmavihara practice:
Add more relaxation to your body and increase your retention times by adding the practice of the four jewels. Center your attention on your heart and hold another being in your field of awareness. Allow your heart to soften with passionate sweetness as you consider the being in light of the four jewels:
Loving-kindness (Pāli: mettā, Sanskrit: maitrī) is active goodwill towards all;
Compassion (Pāli and Sanskrit: karuṇā) results from metta, it is identifying the suffering of others as one's own;
Empathetic joy (Pāli and Sanskrit: muditā): is the feeling of joy because others are happy, even if one did not contribute to it, it is a form of sympathetic joy;
Equanimity (Pāli: upekkhā, Sanskrit: upekṣā): is even-mindedness and serenity, treating everyone impartially.
When we dedicate our heart practice to others (including adversaries), we call in wisdom and heal negative karma. Adding this heart practice is valuable to increasing your inner-fire and recalibrating the nervous system.
3. BLISSFUL INHALE
When you are ready to breathe again, inhale fully and hold for as long as the fire feels healthy - do not allow yourself to become too dizzy before exhaling. Witness the electric fire like two snaking dragons, or electric fountains, climbing up from your sacrum, into your gut, up through your heart, into your throat, through your third eye and out through your crown.
When the electric fire snakes out through your crown, imagine that a legion of guides, guardians, divine beings, Buddhas... imagine them exploding with joy for your success, their blissful love raining down above your head. The nectar of their bliss drips down into a flowing fountain that snakes like two dragons down through your crown and into your body. Witness your body as the divine vessel for the two dragon energies.
4. REAL-IT-IN EXHALE
When you are ready to exhale, imagine your exhaling breath zips your energetic body closed, drawing your expansive spirit body back in from your crown down to your roots. When the dragons do their work, our energetic body becomes very expansive. Practice reeling it back in at the end of each round.
Repeat this process (steps 1, 2 & 3) two additional times. For best results, do three rounds each morning when you wake up. Practice on an empty stomach when possible.
WARNINGS: Do not do this while swimming, underwater, in a shower, or anyplace where suffocation could happen. Do not do this while driving. You'll feel lightheaded and dizzy. Do this at your own risk.