4 ground exercises to strengthen my left side

Shannon and I went to John's today for a jump lesson, and he had vertigo once, so had some ground exercises and very quickly identified what was going on. It was eerie how quickly he was able to identify everything (and explain it's source) without even seeing me ride, and that it was identical to Shannon's observations over the past month and a half or so. He suggested that I stand on one leg (the right one) and first hold my left leg out until it is stable, then start moving it around so that it is independent of my hand. Second, get a stress ball and squeeze it with my left hand (which is weaker than my right, and probably why those fingers are always opening). Third, put some big rubberbands on my left forearm with my sleeve pushed up, attach them to the breastplate/martingale strap, and then my left arm won't be able to cross over the neck or move too far up the neck without the rubber band tension reminding it to stop (in other words, the rubber band tells me what I can't feel, like Shannon can do in a lesson but that I reinforce when I'm alone because I can't feel where that arm is). Fourth, try doing more with my left hand. Like brushing my teeth or grooming Charlie - the left side is basically atrophying because I use the right side so dominantly. Then he had us warm up by riding in a circle in between two standards, so I HAD to steer Charlie properly. Then we jumped a cross rail with that same hard right hand turn through the standards to the right to the fence, so I had to make the right hand turn in a hard way three times on the circle. Then we jumped two fences in a modified figure 8. Same exercise here with the right hand, only I had more space, and to the left, the focus was on bending his neck to the left. This one was awful because out of, I don't know - 12-20 times - I maybe landed on the correct lead twice. Even a 50/50 chance would have better results. These exercises worked because of just the slightest difference in the wording of what I should do - pull my left elbow BACK. It prevents my left hand from crossing over his neck, it acts like a half halt, and it steers. But when I think pull on my left hand, I pull it up or forward or over. The other tip was to act like my right elbow was attached to my hip, making a hinge. I can still open my right hand, but I can't lift my elbow out. And then after I was able to turn to the right again, the next level of refinement was to ask for the canter to be bigger first, ask with my right leg, then pull the left hand back. This got Charlie to come around the corner very well balanced, and it made a huge difference in our approach to the fence. I think these are the same things as before - ride from the outside rein, bend, connect - but something about having vertigo suddenly accentuated all of it, and both Shannon and John were right in now that we've identified it, we can fix it.