It sounds like you're doing some of the behavioral elements already....one of the others I learned for milder depression was just laughing. You just go into a room by yourself and start laughing. It sounds weird which is part of what makes it easier to start laughing. You're supposed to do it for like ten minutes just like you would exercise...I can never make it to ten but even if you can pull off three minutes or so it helps.

Of course if you're past the point where you can laugh this one doesn't work so well...

Then you bring out the big guns.....you double up or triple up stuff you like to do. So combine things like music and petting your cat but add a third thing like a food you like or just a smell or something visual like pictures of friends or travel destinations....but try to get at least two if not three sensory Inputs going at once.