Ok, here's my list, but it's not foolproof (hence right now because I'm currently dealing with it as a type).
1) Music (like others have said): I usually put on stuff that matches my mood because it makes me feel like I'm not alone.
2) Cats: they're pretty awesome when they want to love you
3) Driving: I live somewhere where I can jump in and be in the ocean within an hour. Also, driving around the city is good too—with the music blasting. Also, maybe treat yourself with a smoothie along the way or something.
4) Gym: this is very recent for me because I have a lot of trauma from exercise (it was used as a punishment when I was a child), but I like going somewhere with AC and just having something to do. Also, I'm a self-harmer, so feeling the pain actually makes me feel better.
5) Mall: this can be good or bad. Good - there's stuff to do, you can get a pretzel and look at cool things. There's also a movie theater in mine, so you could do that. Bad: people and crowds, depending on when you go. Also, I'm bipolar, so I tend to spend money when I'm manic, so it's not the best place for me when I'm up.
6) Meds: I still haven't found much that works yet, but I just got put on new stuff, so we'll see. Also, as people have said, do wonders! It's the only way I can shut off my brain sometimes.
A lot of this is trial and error, so you just have to see what works for you. Good luck!