I posted my HIIT workout here, and the benefits of it here. I've been at it for awhile and decided to challenge myself more with a new routine. Remember, your body is amazing at adjusting to workouts, which is why we hit plateaus so often. You have to keep switching it up and pushing yourself in order to see results.
So, here is my new HIIT workout. Remember to warm up and cool down. I warm up for 5 minutes at level 4, and cool down just the same.