When he moves faster, she's left with either falling behind or keeping up, so she gently nudges Impala in the side.

"Let's go, please," she says, her voice sounding less than confident. Impala doesn't even seem to notice the nudge, and Christine blows out a frustrated breath. Again she presses her foot to the horse's side. "Come on," she encourages her, and the horse finally walks a little faster, moving to catch up with Dean's horse. Christine can't help but smile proudly. It worked!