Recent research shows there is a big benefit to keeping pets. One benefit is that it helps relieve stress to those who like having animals around. The medical community is now using medically approved class of "therapy animals," mostly dogs that are brought to visit folks in nursing homes and such. Another benefit comes from walking your dog. You both get fresh air, social interactions, and exercise. You might want to include that as part of your P.E. program. Pets make good companions for lonely people too.
The most popular pets are dogs and cats, but there are also lots of people who have fancy pet rats (my family does), gerbils, turtles, fish, hamsters, ferrets, guinea pigs, and various birds. We also have five cats, two dogs, a cockatiel and finches, two cows, and four goats. I include the cows and goats because we bottle fed them and they are very much like pets. We also have chickens, ducks, guinea, and geese, but they really are not pets. They do not come to us. Well, the geese do, but that is only because they want to bite us; nasty little fellows.