My Blue Lacy is a natural header and most of his breed are bay dogs for wild hogs. He was trained to fetch and drive by a pro trainer. Since he is my first cow dog, I wanted someone to teach the dog and I at the same time.
The trainer used a cane (staff) to block the dog from going around to the front. He used a small pen and had already taught the dog that the cane was the stop sign. Once the calves moved away, the dog wanted to run and head, but the trainer stopped him and kept him on the back. If the calves moved too fast, the trainer said, "Get Around" and let him head the calves. Soon, the dog learned that he was in control, even if he was driving. Headers are worried about losing the herd, but can be effectively trained to drive and should be allowed to head every time the herd gets too far ahead.
Most of training involves giving a command while the dog is doing something you want done.