I think Millie being interested in her ball is a good thing, as Lescef says, but I agree with you that you should try walks without the ball as well. Bonnie is ball obsessed too , which has been a great distraction tool when training and she absolutely loves a game of hide and seek with her ball. It's been a fabulous training aid but we found her obsession worrying and did as you are doing. She has shorter walks with her ball, in busier areas like parks; great for recalling her, teaching her to heel, stop, touch and distracting her from anything we need to (including cats and fox scents). She then has a longer daily walk in the woods, where she can just run and track anything without distractions, no ball. She loves both types of walks and it means she isn't ball obsessed on every walk xx