I have a 6 month old Aussie Shepard that I just adopted. She sits and comes and is loose leashed trained pretty well UNTIL she sees something she really wants, then ALL the training goes out the window. She is a pretty stubborn pup and seems used to getting her own way. She would certainly run across the road if not leashed if she thought it would get her what she wanted. How do I stop this puppy from ignoring my command?