Yes, your cardio work is continuing to progress. Treadmill sprints or a speedy jaunt on the stair stepper might not sound like a ton of fun, but remember why you started. Ramping up the intensity for a sweat-filled session will help you shed unwanted pounds and increase your heart's ability to push blood to your working muscles.
Go as hard as you can, but remember that you have to hold your pace for six minutes. You won't be sprinting, but you won't be jogging either. It's a difficult pace to find and maintain, but push through the pain. Think about how good you'll feel after it's over, the envy you'll evoke at the beach, or the five-minute rest that's coming up.