Laughter. Even if you don't feel happy or cheerful a nurse in hospital told me if you smile and laugh even when you find it hard to do so you brain will eventually take the severity away from your negative emotion and leave you feeling a little less distressed. I guess this one takes a lot of time and practice tho.

Similarly tho, and going on from the 'opposite emotion' thing what I do is turn my stressful situation into a joke. People think I'm sick. I can sit there laughing at some of the worst types of things. It's not because I think they are funny but if I don't laugh I end up crying. And crying hurts my brain a far lot more after I've stopped!