This is quite amazing! And it's obvious that you're not only dedicated in your training, but also in your craft, which is wonderful.
My admiration and respect to you. I think I will start a similar training myself, I've had profound experiences with pain and physical reality, and this feels like the natural next step.
I have a couple of questions to ask: do you feel this training has provided you other benefits such as greater stamina, endurance and flexibility? If so, do you think it's the direct result of the still brush training or rather comes from Qi Gong practice, or a balanced mixture of both? I've found that a lot of our physical limitations are related to the pain we feel when we engage in a particular activity or adopt a certain posture for prolonged periods of time, so I'm curious if conditioning the body this way would actually make training easier to sustain.
Thank you in advance! Blessings!