1) The one I mentioned (don't start out your day with support) is important. Have breakfast first, drink your coffee, read Hacker News.

2) Take a break. We answer support even nights and weekends, and this is important in connecting with users early on, but on nights when you aren't in tip-top shape, just don't do it.

3) Complain to your co-workers. Venting helps.

4) Strenuous exercise really helps. Nothing like a 20 mile hike to clear your mind.

5) Vacations without internet access.

And of course, make your product better! Fixing bugs is usually a better way to stop complaints than adding features. People thanking you for your work is a soothing balm, and you can eliminate a lot of harsh complaints. I'm not sure how actionable the advice is, but hang in there and do good work, and ceterus paribus, it will be a fulfilling existence.

This series Dexter has some great tips.