Is zazen a process of undoing and to what extent can that process be a conscious one?

We describe our practise as 'just sitting' but how accurate a description is that of a human being on a cushion?

I can't answer these questions entirely here but this is the first salvo.

When I sit in the morning or in the evening, sometimes my head feels as if it is spinning with rationalisation of the day's events, with anticipation of events to come, with dreams of the future, regrets and so on. There is a direct correlation between these states and physical being whether that is a slumped lower spine, tension around the neck and shoulders, hunching. Perhaps all of these physical and mental, or rather psychophysical states are positions of rigidity, habitual positions we take in order to attempt to grasp something of our lives...perhaps.

We are directed in zazen to sit upright, our spines supported by a cushion that also tilts our pelvis forward. We create a stable triangular base with our legs, full or half lotus or the Burmese position. With our hands we form the mudra just below our navel. Personally I then sense the crown of my head as the top of my spine and adjust my posture so that I find balance with spine aligned vertically in space, not pressing or pushing, just gently sensing it this way (this is not always reliable which is why a teacher can help us to lose bad habits and find that ordinary aligned position.)

Then we sit, comfortably, allowing the posture of zazen to educate us physically, mentally and finally to free us of both of those bindings. The key aspect of practising zazen is to notice what it is that is preventing you from practising zazen which sounds like a contradiction but when we sit we notice that we are holding tension in areas of our body, that we are continually returning to a familiar pattern of thought. Noticing these aspects has the effect of freeing us from them. But actively trying to diminish tension or avoid thinking has the opposite effect of compounding these areas of rigidity into an immoveable object. The key is to permit the state of 'just sitting' to manifest itself without interfering.

Sometimes, when we've ceased to hold these perceived mental and physical states captive, we can become completely free in this instant of the present. Edges vanish, the whole being sits calmly in the same state of experience or reality as the entire universe. A very plain, very ordinary state of existence with nothing added to it, nothing preventing it from being.

It is a subtle practise, a lifetime's work but it is also immediately available to anyone who wishes to sit on a cushion and practise it.