‘Stopping the mind and contemplating quietude is pathological; it is not Ch’an. Sitting all the time constricts the body – how does it help towards truth?’ (The Platform Sutra of the Sixth Patriarch)
I remember reading this in my first winter at Tassajara, and feeling vindicated that I was not enjoying the amount of zazen I was sitting. Of course, it was because my body was being constricted! To be fair, as an active person since childhood, sitting still never came naturally to me, and it took that whole winter to gain the flexibility needed to sit as much as we were doing (six periods and three meals in a standard day). These days I read it a little differently: it is easy to set this against Dogen insisting that zazen is the only practice, but, with typical zen slipperiness, I would say that they are not mutually exclusive. And everyone agrees that it is not about stopping the mind.