negative – adj. not positive or desirable
companion – n. someone you spend a lot of time with
collar – n. a line that attaches around the neck of an animal
stress – n. feelings of worry or nervousness caused by difficult situations or problems
hormone – n. one of several chemicals produced in the body that influence growth and development
pessimistic – adj. tending to believe that the worst will happen
respond – v. say or do something as an answer or reaction to something that has been said or done
boss – n. person who leads a group of employees
motivate – v. stimulate someone's interest or enthusiasm for doing something