Sometimes you have good reason to be depressed. I don't think depression should always be treated as if it were something to get rid of, like a cold.
This suggestion is not for everyone, but has worked a little bit for me.
I adopted a cat from a shelter, and got lucky. He wants constant attention / petting, and shows great joy when I pet him and feed him. Having even just one living thing around you that is happy and shows affection to you can be very healing.
I would warn against adopting unless you are certain you are stable enough to care for an animal and not neglect or abuse it. Many shelters seek temporary foster homes and you could try that out first. Some shelters let people come and take dogs out for walks.