Preferably aggressive ones. Fencing, wrestling, martial arts.

Generally, strenuous physical activity is very good for concentration and relaxation. Sports are good. Chopping wood is lots of fun. Competitive Timberman Challenges are probably the best option.

really?! I want to do one, how does ones start with chopping wood in San Francisco?

Just go to any park with an axe and run away when you see the cops. Drum circle disruption is a good cool down activity.