If you have a bokken handy or can grab hold of a suitably sized broomstick you have yourself a workout that challenges you to think how you use your body in three-dimensional space and, as a result, forces your brain to remap its internal wiring. Blade is a workout that's fun to do, immersive in its approach (which unleashes a whole lot of other mental and physical health benefits) and physically engaging.
Extra Credit: 1 minute rest between sets.