I’ve started to meditate. If I feel that my mind’s just buzzing with random thoughts (and I don’t have much else to do), I’ll just lie down wherever I am and stare at something, listen to something, or concentrate on something until I’m feeling calmer. It’s a little hard to do it for a long time – stuff starts to ache or itch or distract me, but that’ll get better with more meditation.
BTW, forgive me if this sounds lame to anyone. I’m only saying that because that’s what I used to constantly think of other people on my friends list who were also doing similar things.