Self-restraint can be hard to effectively manage. There's been an ongoing debate about the notion of catharthis and whether it works to help us relieve emotions or not, for example. A recent article in Wired.com discusses the issue a bit more:

My favorite experiment involved movies. Two hundred and thirty nine subjects were given a choice between a virtuous apple and a hedonistic chocolate bar. (A slim majority chose the apple.) Then, they were offered a selection of movies to watch, from Anger Management (an anger themed film) to Billy Madison (a non-anger themed film.) Interestingly, students were significantly more likely to choose the angry films if they’d first chosen the apple. And it wasn’t just films: another experiment found that people who exercised financial restraint – they chose a gift certificate for groceries over one for spa services – were more interested in looking at angry faces.

But just because practicing self-restraint can lead to some anger-related experiences, it doesn't mean that we should forgo self-restraint entirely. Over time, not succumbing to urges will weaken the power of those urges. The implication is that if we can practice self-restraint consistently, we'll be reducing how often we feel angry and/or seek out anger-related stimuli.