Aye, I have to agree about the cathartic nature of aggression at times. Sometimes it just makes you feel a lot better to get into the gym and pound the weights a bit, and maybe get in a good run or even some time on the punching bag. This is one reason I miss a prior appartment gym that had some good punching bags, always good to have one close at hand
But also, I do keep a couple of journals for various things, and it does help a lot. The largest is that it lets you take the thoughts from your day and put them somewhere that you may look at them, understand what has happened better, and find your opinion/view on them. From there you can act on the days events, or feel more comfortable putting them away. Recognizing the good, fixing the bad. It's all good stuff.