Once you notice you're annoyed, stop for a second and ask yourself why you're annoyed, what caused you to get annoyed, who did it? Then ask yourself, "how can I change that? Could I prevent it? Can I still prevent it?".
Listening to mindfulness meditation stuff is not for me, I get restless and can't concentrate.. If you can, I think it might help. If not... well, atleast you've tried.
Other things I do is listening to music that makes me happy. Silly songs, happy songs... Not angry hard core screaming stuff, even if I love that shit, cause it won't make me happier (well, actually it does sometimes.. but whatever).
I read happy things, novels, webcomics, watching kitten-gifs... Basically, happy stuff.
This might not be your cup of tea, normally it isn't mine either... But this song makes me so happy, makes me dance, makes me bounce up and down and smile.