Motion and emotion are directly related. Remember being in a state of fear or anxiety. Not exactly an emotion that elects smooth movements does it? How you approach an animal or another human is limited by the emotional state you are in at the time. During our days of NLP training one of the best ways for breaking the states of the people in our group was to make them dance wildly. Movement can directly affect the emotional state. If someone is depressed their posture is more one of flexion. The quickest way to make a change is to invite them into a different posture. Animals are like walking biofeedback machines. They pick up on your emotional state and can respond accordingly. Listen along to how motion and emotion are so important.