Hard (difficult) dressage lesson

John started by making me put my hands behind my back, lean back, and then roll my neck. He said that I'm coming in so tense, I'm curled up and balled up, and that means that when Duke pulls on me, my whole body tilts forward and back, because I'm not loose in my elbows and they can't move independently from my body.
It felt horribly awkward to roll my neck around and relax. It was awkward how awkward it was.

Then John made me a square and we started the lesson by walking shoulder in along the side, then doing a walking turn on the forehand at each turner, into another shoulder in. It probably took me three trips to figure out the feel, and then - only once - Duke got stuck, froze, I used outside leg, and we moved on. The hard part was - going right - doing shoulder in but also keeping him bent to the right and then turning in time to make the next corner of the square.
Then we turned it into a 15 meter circle - sort of but using the four center points of the square as the circle points, and keeping that same feel. Then a circle, then back to the four corners.
Then we did it at the trot. Yikes. It was so much faster and harder. Then we changed direction, and we didn't need to work as hard going to the left as we had to the right.

Then we switched to 20 meter circles and did our canter work, which for some reason just felt brutal today. Even though Duke was round and stepping decently under himself, at the canter, he was just HANGING on my hands, and my choices were either to slip the reins or let him pull my ass out of the saddle and thump around.
I had to hold his head with my hands, grip the reins like I was riding a rocket into space, and then tuck my pelvis and push my butt into the saddle.
John said Duke needs to understand that he can't keep taking-taking-taking the reins and then look round, but I don't actually have enough grip to make a turn or do anything with him.

It was a great lesson. Also, we established that John can't talk fast enough to tell me every aid. When he tells me to do something with my right leg, for example, my left leg just quits doing anything.