Enlightenment is not some special state of mind
The state you are in when you have 'right posture' is itself Enlightenment.
These are the words of Suzuki Roshi, the foremost interpreter of Zen for the West, speaking to a group of close students some 25 years ago..
Clearly Suzuki Roshi is not referring to some mechanically correct body position when he speaks of 'posture'. He is actually professing to his students his profound confidence in the unity of mind and body. His message is, that though they may not appear identical on every level, mind and body are intimately and inextricably interwoven and interdependent aspects of the unified whole.
We find ourselves however in a culture and historical era where 'mind' has come to be regarded as separate from and senior to 'body', and although the mind is quite fascinated by such concepts as mind\body unity it is rarely willing to surrender its superior position.
Historically we have some of the great minds of our civilization to thank for this predicament. St. Augustine, embellishing Plato's ideas of eight centuries earlier, argued eloquently for a dogma of salvation through transcendence of the 'profane' body.
Christian theology prior to this was basically holistic (holy) and the Old Testament is abundant with lines like; "they stiffened their necks so they would not hear the words of the Lord" ( Jeremiah 17:23) suggesting an understanding of 'bodymind' unity. The philosophical surgery excising mind from body was completed in the seventeenth century by Rene Descartes. His proclamation, "I think, therefore I am", made a telling epitaph on the tombstone of wholebeing.