I made the mistake of sitting after lunch. Sleepy. I am feeling sleepy. Not liking having to sit up straight, and still. My body's rebelling with aches here and there. Under the tip of my right foot, in the neck, right shoulder. I refuse to give in. There is wisdom to be gained in not moving. Breath's helping, only a little. The un-indulged tiredness feels like Chinese torture. Thoughts come and go. With each, I escape moment, for a short while. I could latch on, and distract myself, some more. No, to stay present, with the torpor. Noticing I am not 100% there. My brain's doing some interpreting of the moment. Misrepresenting, lumping each sleepy second into one big stretch called "I'm so sleepy, and I want out". Leaving little room for finer attention, to the subtle changes. Outside noises, take turn to break into the rigidity. Each time, giving awareness a fresh start, a new chance to focus, and explore 'sleepy'. After a while, fresh energy starts flowing. Mind, no longer dull, can start working with breath again, and engage in satisfying work of concentration.
Although Vipassana practice makes room for slight shifts of the body during meditation, I find I am getting more out of sitting when I take on the stillness of Zen. In the discipline of motionless body, there is no escaping the moment.