If you were a student of a Kenjutsu dojo, you would be taught how to wear yourself out in your apartment with your bokken, suburito, and hokkoku suburito.
If you have some secluded forest land available, trim limbs from saplings. Or cut the tops from tall feild plants. If you learn how to cut using a bokken, you will be able to eccelerate the leading 6 inches to a speed that can snap clean green 1/2" to 1 " brances or similar things.
Check in your local area for a Kenjutsu Dojo, or a Budokia that teaches some school of Kenjutsu.