Lunging your horse should not look like you are flying a kite and the kite is trying to pull away from you. Remember all ground work translates to your ridden work. If you have allowed your horse to run around in a circle, haunches flying to the outside, head pulled to the inside fighting against the resistance, why would you expect anything different under saddle? Lunging should not be about getting the fresh off, wearing the horse out, running them in circles. It should have a purpose. The exercise should ask questions of the horse and allow them to look for answers. I like doing a lot of transition and direction changes. My goal is getting the feet and brain attached. Rarely do I spend more than 3-5 minutes lunging. The line is no different than your rein. You should be able to hold it with your thumb and forefinger and not have it pulled from your hand. Keep your elbow and shoulder relaxed. Keep your feet moving in small circles. Work with a plan. Don’t make that plan chasing a prey animal prone to flight around in circles until it exhausts itself. How well do you learn after you’ve been stressed out? Help your horse help you by being a thoughtful leader.