Lena Wedenmark is a dressage instructor based in Wellington, Florida. I love this quote from her:
Do yourself and your horse a favor and stop trying to control his head and neck. Just let them do what they’re going to do, including coming up and out from time to time. Just because you’re doing dressage does not mean your horse has to first be round in his neck. His head and neck are the last part of the connection, and trying to pull him in is the very thing that sets you on the wrong path and damages your ability to learn how to ride. Work on yourself according to the rider’s training scale, and connection and control will come naturally.