If the dog is on his left (as she should be) then when he turns left she will have to slow down to stay out of his way. When he turns right or does an about-face to the right, she will have to hurry to keep up with him. These maneuvers will pique her interest and help keep her focused on him. Ideally, her front legs should be in step with his legs, but that is a goal to work toward, not something that will happen right away.