I just got finished with a guided body contemplation meditation by Ajahn Achalo and had an experience that was uncomfortable yet revealing. We reflected on the earth element in the vertebrae and teeth to good effect but when the ajahn asked us to contemplate the blood coursing through our bodies I became immediately nauseous. Just the thought of my body being soaked in seven liters of blood was too much for me to handle for some reason.
I have only ever experienced this kind of discomfort during body contemplation but the intensity of this was such that I was literally squirming on the cushion. Clearly this merits more work and surely points to a strong attachment even if I can’t quite make sense of it yet.