The original meaning of asana is "seat." The postures of yoga are excellent ways to develop a healthy sitting posture, as well as in standing and walking.
This list can guide you in checking relevant aspects for a healthy, comfortable posture that enables deep, relaxed breathing & samadhi.
* Sit with enough cushion that hips are level with or higher than the knees.
* Support knees if necessary.
* Relax buttocks, thighs, legs, & lower back into sit bones so they receive the body's weight.
* Area around sacrum is soft (neither pulled forward nor stuck behind).
* Roll shoulders back & expand outward. Keep soft.
* Energetic lift (not with muscles) up from hips along spine into neck & base of skull and up through the crown of the head.
* Gentle stretch along the back of neck so that there is a slight downward tilt to the face and chin is tucked (not jutting).
* Hands in comfortable, relaxed position that doesn't pull shoulders down or forward.
* Eyes gaze softly past the nose.
* Pull up & relax kneecaps.
* Stretch out sit bones.
* Gently roll hips forward (slightly) without tightening sacrum.
* Separate femurs from hip joints
* Relax & soften temples inward.
* Relax inner ears towards each other and hollow downward into throat, chest, & belly.
* Relax jaw hinge below ears.
* Relax & soften tongue back into its base (so that isn't pressing teeth, though it may gently connect with palate).
* Relax soft palate upward.
* Consciously take deep, full breaths for at least a few breaths and no more than a few minutes. These breaths shouldn't be forced; always work within the body's current limits.
* Gently encourage "four part breathing": first lower belly and lower back, then up into collar bones & upper back.
* Body becomes like a cylindrical bellows, hollowing inside outward in all directions. Breath drops into pelvic cavity and fills upward. This occurs receptively rather than forcefully.
* The "hollow" fills with pleasant, life giving energy that radiates throughout the body.