I've kept one for years and can see my progress regularly. I can also remind myself of tools I've used in the past to get through certain situations. It may be helpful to keep separate journals, i.e., an anger journal, a gratitude journal, etc. A gratitude journal is especially beneficial to keep on a daily basis. It reminds us of all the good things we have in our lives.
Exercise is a very good way of working off any kind of stress or anxiety.
Caffeine and sugar are known to add to anxiety symptoms. It's best to avoid them altogether or keep their intake to a minimum. If you're upset with a particular person, paint their picture on an egg. If you're going to a scheduled event, try doing a relaxation exercise an hour or more before the event. The more relaxed you start out, the more relaxed you're likely to be as the evening progresses.