I have not volunteered at a shelter or Humane Society, but Vi Co Bi and I have helped with a few dog transports (to help take some great dogs to a caring foster home). Currently, we are fostering a 6 month old Great Dane puppy, named Asgrim. I can tell that doing those things have reduced my stress, and I have a better outlook on life and the world in general.

Here is the thread about Asgrim:

Dog Rescue: My First Foster