So I've learned to notice my cognitive distortions (see link in subject) and combat them. This has shortened the duration and reduced the severity of my depressive swings (not that a regular reader of my LJ would notice...). However, the same tools that allow me to shut down negative thought loops can also strengthen them when something negative happens. It's interesting because my initial response is somewhat neutral but I can feel myself trying to convince me that I should feel bad about it.
Wow, I need to go home rather than go on about this negativity shit.