Day 12: Where are you?
If you did cardio kickboxing on day 11, do your cardio speed bursts on day 12, and vice versa.
If you are doing cardio kickboxing, try last week's workout, or look on netflix for the 10 minute series on kickboxing. It's Keli Roberts, which of course gets my recommendation. Do the whole video,not just 10 minutes. Great workout.
If you are doing speed intervals, try to increase your full speed times to 25 or even 30 seconds of bursts every 5 minutes, but increase your recovery time to 45 seconds before going back to a moderate-comfortable pace. Try to do 5 or 6 blocks of intervals with recovery and moderate tempo in between.