That's what I do Tas, give burst of speed every now and then to increase the heart rate.
Are you sure you don't have a Cross Trainer? I did use that at the Gym before my membership ran out and they are very hard to use, I could only do 10 mins on it.
Anyway I am going for an hours walk this morning (before my weigh-in) then I will do 20 mins on the Airofit before dinner tonight.
Have a good day, and if you have to pick yourself up of the floor when you fall off that's also a form of excercise.