A good technique to help w this is "affective labeling" (sorry, citation needed, I think I got it from one of Anne Laure Le Cunff's typically awesome newsletters/posts). Set a 5m timer, start writing words that describe your emotions and don't stop writing for even 2s till the 5m are up.
As an aside, I miss the slashdot ability to optionally assign a property to a vote. It would be neat to have some sort of indicator in addition to the greying out of downvoted or flagged comments to show specific types of upvotes. This has obviously proven to be the better system overall, but it has its pluses. Too bad it also had a bunch of swastikas and 4-Chan-esque trolls.
Slashdot had, for many years, fairly insightful commentary with that system. The fact that it has since become less insightful is, I think, less a reflection on the voting system in comments and more on people moving from the site wholesale for various other reasons.