I started working out again last week and i'm starting to notice my energy levels rise and my mood improve. I'm also starting to look better, which is making me feel better about myself.
If you don't exercise regularly, try it and stick to it for a while. Start out slow so you don't feel super sore the next day. Begin to challenge yourself when you notice your workouts are getting too easy.
BTW, hitting a punching bag is fun and a great full body workout.
For more exercise ideas go here: http://www.depressiondodging.com/irritabilityandexercise.html