In the actual moment, where the pain is too much, three things help me, all discovered during a particularly bad patch this time last year. First, if you can - if you have the space and privacy to - scream. The mental/emotional distress gets such that it is very much physical, and I tried letting off a scream, as I would if the cause were some externally caused injury. It felt strange - even on my own, I was inhibited - but it helped a lot, a sudden release of pressure, and I was soon walking around the empty house, just doing chores, those feelings would hit, I'd let out a scream, and they'd start to disipate. When I couldn't scream, I'd snarl. It still requires a certain privacy, but I was trying to let the feelings have a physical outcome. And then writing and writing and writing. Just what I was thinking and feeling. Again, I felt the release of pressure, or the neutralising/discharging of an electro-static build up.
On a more day to day level, I try listening to myself. If there's something I want to do that might help, no matter how silly I may feel or inconsequential it may seem, I do it.