I have one of those heavy canvas punching bags. I think I paid $90 for it, but you might find one at a garage sale or on Craigslist for less. Whenever I get to where you are, I hang it up in my garage and beat the snot out of it with broom handle or a baseball bat. If I'm really far gone, I stick pieces of paper with words and/ or pictures on it. Wear gloves unless you have good calluses. You could just punch it, too, but that is a lot of work, and you can hurt yourself if you don't know what you are doing. Besides, a bat makes a good, satisfying noise.
I have also been known to go to the pistol range, and write things on the targets with a Sharpy. It's amazing how much better I shoot when I'm inspired. Shotguns and clay pigeons are good, too, unless missing makes you mad.
When I lived in the midwest, I worked out a lot of frustration with a brush hook, but now I live where you have to beg trees to grow, so chopping is not an option.
I second the sports massage therapist, the one who isn't relaxing but knows how to release tension.