Zazen is the practice of attending to experience as it presents itself, with and as the whole bodymind. While the mind may wander off into thoughts of the past, interpretations of the present, and speculations concerning the future, the body is always right here and right now. Thus, zazen begins with the body practicing an upright and attentive posture.
The main point of zazen posture is to attend, and not to merely take on or force the body into a particular position in order to look or feel "holy" or "like a Buddha". Dogen zenji says in the Fukanzazengi: How Everyone Can Sit, "You cannot fabricate Buddha through sitting or lying down". You take a strong, stable, and open posture to practice, to open to your actual experience, to understand yourself, to enter and manifest the Unborn nature, and realize yourself as Buddha. Making a "big deal" out of it by dreading a difficult posture or romanticizing it is all unnecessary.
The bodily posture should be balanced, grounded, and open. The full lotus (kekka-fuza), or half lotus (hanka-fuza) are optimal for this posture of an aware bodymind and so you could experiment with those first.
Turn to sit facing a blank wall. Sit on the front edge of a zafu (round meditation cushion) or any thick and firm cushion that you might have at hand; if you sit too far back you will put too much pressure on the back of the thighs and cut off circulation. Rest the knees on a zabuton (flat padded mat) or blanket so that the knees and buttocks form a tripod of support for the upper body. Lift up one ankle with the hands and pull it up onto the thigh of the opposite leg; the line of the toes should align with the outside line of the thigh. It really doesn't matter very much which leg is uppermost. Allow the foot to rest in the hollow of the thigh and then try to bring the other foot up to the same position on the other thigh. Bring the feet in as close as is possible. This is the full lotus posture or padma asana. If this is uncomfortable, then bring up only one foot and tuck the other underneath the leg. This is the half lotus.
You will probably experience some discomfort after holding this posture for a while. Stop "holding it" and just sit with it. The idea of the discomfort is much worse than the actual sensations. As you continue to practice, the body will settle into the posture, ligaments will become more flexible, tension held in the hips, thighs and calves will release, and the posture will become not only comfortable but will have a steady, joyous quality. Basic stretching exercises will be helpful in alleviating undue stress on the muscles and increasing flexibility. Sit in the posture at any opportunity: to read, listen to music, and so on.
If neither the full nor half-lotus postures are suitable as yet, you can simply take the "Burmese" or agura posture in which the knees contact the zabuton and one ankle is placed in front of the other. If this is not suitable, sit in seiza (a formal kneeling posture) on the zafu with the knees spread and the big toes of each foot in contact, left over right, behind the zafu. Again, keep the knees about four fists apart so that there is a grounded quality to the posture.
If you have severe back or knee problems you may certainly also use a chair or stool; in this case sit well away from the back of the chair with the feet flat on the ground. If you are very ill, you may practice by lying on your back with your hands over the hara in the shashu mudra, the right hand folded to form a fist with the left hand placed over the right, the left thumb tucked into the fist.
The hands can also help us to practice zazen. Put the right hand palm up so that the wrist is resting on the right thigh, and, if you are in the full-lotus posture, the backs of the knuckles are on the upturned heel of the foot. In Burmese or agura posture the backs of the wrists should rest on the upper inner thighs. Place the left hand so that the knuckles fit behind the knuckles of the right. Bring the blades of the hands in against the tanden (the area of the lower belly four finger widths below the navel) and allow the thumbs to touch lightly in a natural arch above the palms.
This is the hokkai-join, or dharmadhatu-mudra which means the "gesture of reality". The mudra will help you to notice how you are. We should be aware of whatever mental state arises as it arises; however, if we were able to do this completely, we wouldn't need to start with feeling the breath. Mental states and bodily states arise together as bodymind is not separate. Therefore, bodily states can remind us to recognize our mental state. If mindfulness dulls, the hands will slide forward and the thumbs will drop. If your practice is judgmental and goal-oriented, the thumbs will press against each other tensely. A stable and open bodily posture is a manifestation of a stable and open mental posture.
Now open the shoulder blades and any tension being held in the shoulders. Straighten the head and draw the chin back slightly. Exhale and bow forward from the hips toward the wall, keeping the body aligned. Slowly straighten again while inhaling. You should find that the pelvic area has thrust forward slightly and that there is a very slight concave to the lower back. This will support your back. You do not need to tense your shoulders or try to somehow hold yourself straight with your chest. When your posture is aligned correctly in this way, the upper part of the body should feel almost weightless and the lower part extremely grounded and settled.
Exhale deeply through the mouth and place the tongue against the palate, with the lips and teeth now closed. This will create a slight vacuum in the mouth and so the gathering of saliva in the mouth will be decreased.
Place the eye gaze about one-third up from the bottom of the wall to your own height and allow a soft gaze; that is to say, do not stare or focus on the wall, but let the gaze fall "through" the wall and be open to peripheral vision. Do not keep the eyes wide open, or you will be easily distracted. Do not close the eyes or you will be scattered in the random hypnogogic colours and images that arise, or you will become dull and sleepy.
The body is the mirror of the present moment.
In this posture, just sit.
The Posture of the Breath
Like thoughts, the breath comes and goes. If anger arises, the breath becomes angry. If sadness arises, the breath sighs. If your practice is tense, the breath is tense. Attend to the rising and falling movements of the lower belly as the breath fills and releases. Each breath is fresh, new - you have never breathed this breath before. The breath is a touchstone through which you can bring body and mind together in the same time: here, now.
Just feeling the breath itself, abandon notions of the breath. Don't even "watch" or "follow" the breathing. Just feel this breath. When you wander into discursiveness and get lost in thoughts, return to just this breath. When mindfulness darkens or sinks, return to just this breath. Practice free from struggle. Don't tense the belly around the breath to make sure you are watching it and thus take on the stance of a "watcher". Don't try to manufacture deep, calm breaths. Just breathe as you breathe. With this breath, you enter into your life.
The breath is a mirror of the mind.
In this posture of breath, just sit.
The Posture of the Mind
As you sit, the mind takes on various postures or stances. It crosses its arms and tries to just wait things out. It twiddles its thumbs. It fidgets and scratches and wriggles. It flails its arms, shakes its fists, and screams. It crouches and slumps among its old memories, its favorite old movies and songs, as random chattering. It bloats with pride at having been "watching the breath" so clearly. On and on and on.
The mind defines itself as "this" as opposed to "that". It agrees or disagrees. It tells itself stories about itself over and over to try to prove to itself that it is real. It takes a point of view and then confuses that viewpoint with what is seen and so blinds itself to seeing clearly. And on and on and on.
The mind is the mirror in which experiences arise and present themselves within Awareness.
Breathing in, breathing out, just sit.
Sit on a zafu or cushion facing a blank wall. If you use a timer or a clock, place it out of sight and forget about it until thirty minutes are up.
Straighten and align your posture: ears over the shoulders, nose over the navel. Release the shoulders. Knees should be flat on the mat or floor so that together with the buttocks a firm base of support is formed. Place the hands left over right in the lap with the inner edges of the hands against the belly. Rest the wrists and allow the thumbs to touch lightly.
Exhale and bow forward from the hips, keeping the back straight. Pause.
Inhale and straighten. Rest back from the hips lightly and exhale, placing the tongue against the hard palate. Keep the chin tucked in slightly. Eye gaze is soft, half-open, and directed downwards slightly.
Sit. Feel the movement of the breath together with the tanden (lower belly). Don't arrange the breath. Just breathe the breath.
When you become lost in thinking, sleeping, hearing, seeing, itching, or anything at all, just notice that and bring yourself back to present experience through feeling this breath.
Practice yourself as you are, right now.