Just wanted to let any newcomers here know how well KBs work your cardio & flexibility. If you're worried you might lose something by just working KBs, check this out:

I started the Program Minimum six months ago after "graduating" from a round of P90X. Cardio & flexibility were probably the best they had ever been in my life.

Saturday I thought I would see where my cardio & flexibility have gone.

Mind you, I haven't been running or hiking or biking, nor doing the endless hours of cardio and yoga from P90X for nearly six months.

Popped in "cardio-x," which is basically a combo of yoga, kenpo jazzercise & "plyometrics," and was pleasantly surprised to see I didn't lack in any category! My flexibility and endurance were all the same, if not better! I just got a little sore in some support muscles from all the punching & kicking, but otherwise, it was a walk in the park =)