Went to the intimidatingly titled Fierce Fitness for kickboxing, which is not to be confused with letterboxing and is way better than shadow boxing. I mean, in shadow boxing you box your shadow. In kickboxing you get to kick and box a punching bag. It's a very satisfying way to work out aggression.
That said, I'm not very aggressive. Twenty minutes of pounding and I felt complete. In the words of the Kinks, I'm a lover, not a fighter.
Okay, some would say a wuss.