In Bhagwad Gita (8.10) Krishna says “ One who, at the time of death, fixes his life air (pranas) between the eyebrows and, by the strength of yoga, with an undeviating mind, engages himself in remembering the Supreme Lord in full devotion, will certainly attain to the Supreme Personality of Godhead.”

The shloka describes the method of achieving spiritual death. The above can be simplified as:
1. Take a deep breath in and fix the respiration between the eye brows
2. Initiate all three bundhs(strength of yoga)
3. Close the eyes to start an inward journey (undeviating mind)
4. Bring the awareness to the heart
The next phrase describes who can do this.
8.11: “Persons who are learned in the Vedas, who chant AUM and who are great sages in the renounced order enter into Brahman. Desiring such perfection, one practices celibacy. I shall now briefly explain to you this process by which one may attain salvation.”
People, who understand breathing techniques, do regular AUM chanting and understand yogic techniques can only practice this.
The next phrase clarifies the exact procedure.
8.12: The yogic situation is that of detachment from all sensual engagements. Closing all the doors of the senses (bandhs) and fixing the mind on the heart and the life air at the top of the head, one establishes himself in yoga.”

The three phases describes how to attain inner happiness and also how the yogic death is peaceful.

One therefore must learn the art of pranayama and chakra pranayama. That is to learn to take the breathing to various chakra areas of the body. Kundalini is the dormant shakti, which you try to stimulate with chakra pranayama. When kundalini reaches anahata chakra (heart) then it has reached the point of no return.

From manipura chakra (celiac plexus), it can return or descend at any time. It is decribed as Swapishi kulakunde kuharini (Saundarya Lahari v. 10) – it can descend to its resting place and go to sleep. The resting place of kundalini is swadhisthana (gonadal plexus). The word swadhishthana means your own residence. So kundalini goes back to its residence and falls asleep.

After reaching anahata chakra, kundalini is unobstructed, unhindered. Thereafter, it does not return. Anavrittim, anavrittim – no return, no retreat. After anahata, there is vishuddhi chakra, and after vishuddhi, ajna chakra. The Ganga flows till here. Beyond this, there is no Ganga; beyond this lies the sea. That very Ganga becomes the sea.
The gist is that at the time of death one should direct the life force through the sushana channel in the spinal cord and fixes it at the ajna chakra between the eyebrows and then meditate with steadfast mind on the GOD in the heart to attain peace.

Lord Krishna uses the word samyamya which means controlling. The procedure involves withdrawing all the inlets of the organs being eyes, ears, tongue, etc. by non-cognition of external objects and focusing the mind in the heart, dismissing all external conceptions while fixing the life force in the ajna chakra between the eyebrows.
From mooladhara chakra to anahata chakra is the dakshinayana path. From anahata chakra to ajna chakra is the uttarayana path. Those who travel on the uttarayana path travel from anahata chakra. Those who travel on the dakshinayana path start from mooladhara.

How to practice bandhs
1. Mool Bandh : Contracting the anus , draw upward the Apana Vayu slowly by practice. Mool Bandh can be usually practiced by sitting in any asana & every type of Pranayama.
2. Udiiyan Bandh : when Prana is made to enter the Sushumna Nadi , it is called Uddiyan Bandh. All the Vital Nadis in the body are located at the root of the naval. Empty lungs by a strong & forcible exhalation. Now contract forcibly draw up the intestines & also the naval towards the back, so that the root of the naval rests on the point against the back bone.
3. Jalandhar Bandh : This bandh is practiced along with Internal Kumbhak or External Kumbhak & by pressing chin firmly on the chest & contracting the throat. It enhances the capacity of retaining the breath for longer period.

“5.27-28: “Shutting out all external sense objects, keeping the eyes and vision concentrated between the two eyebrows, suspending the inward and outward breaths within the nostrils, and thus controlling the mind, senses and intelligence, the transcendentalist aiming at liberation becomes free from desire, fear and anger. One who is always in this state is certainly liberated.””