I am an avid dog lover. I have had dogs my whole life growing up, mostly German Shepards.
To me, I think pets provide happiness and joy into our human lives. There is something to be said about having a rough day at work and coming home to an animal that is so excited to see you. No matter what kind of day you have, animals are always happy to see you.
Joy and happiness, from an animal, will lift our spirits when we are down. I think this is important for our psychological health.
I take my dog running, hiking, walking, and to the park with me. There is a bond between us like no other. Although he cannot communicate in words, he can with his body actions and demeanor. We have fun together and whenever I take him to family gathering's he stays right by my side. He is loyal to me because he knows who feeds him, cares for him and takes care of him. Doing things outdoors with him motivates me to stay in shape. At the same time it keeps him in shape. This is good for both of our physical health.
Whenever someone comes to the house, my dog barks to alert me that I have a visitor or something is out of the ordinary. This is great because dogs have a keen sense of smell and hearing unlike any human. I wouldn't even question what he would do if someone was trying to hurt me. The protection he provides is uncanny. I would do anything for him if something was trying to hurt him as well.
If you have never owned an animal before, you will not know what I am talking about. There is a bond and love between human owners and domestic animals that is indescribably unless you have had the wonderful blessing of being able to provide a great home to a dog or cat before.