Hard to keep up!

Our aunt and uncle just adopted a little terrier mix named Lizzy and Nick and I have had 2 play dates with her. Being that he is also a terrier or TERROR as Mom calls him, they really seem to hit it off. They run circles around me in the yard and it is all I can do to keep up. Then, just to show my dominance, I attempt to mount Lizzy. She doesn't like that very much. Boy, sometimes it is hard being a couch potato when you're running with dogs who are actually in shape!