Pets add a lot of joy. Do you already have a pet? Take them out on walks together more often and make it a routine. Or, simply make more time for playtime.
If you can't have a pet, can you volunteer at a shelter? The unconditional love of animals can really fill our hearts, and can help combat loneliness, among other things.
Go give your pet a big hug right now if you already have one, I say. :)