The other day I was on the treadmill and I just couldn't muster up the energy to both workout and create my own routine. Paying attention to the numbers on the screen seemed overwhelming, but the television was on and I decided to use the TV programming to my advantage. I did a TV commercial interval workout and this little routine got the job done.
Here's how it works: Turn on a TV while doing cardio on a machine. During the programming go at a RPE (rate of perceived exertion with 1 being a super slow stroll and 10 being a full out sprint) of about 5-7, during commercials try and keep your RPE around 8-9. Since most commercial breaks are about 3.5 minutes long, this gives you a few good bursts of high intensity cardio every 10 minutes or so. This cardio variation is definitely not something I could (or would) do each time I'm on a cardio machine, but it was a nice change of pace (sorry for the pun) and nice to focus all my attention on timing my intervals. Plus, since I don't really care about the commercials, I was able to really focus on pushing through the 3.5 minutes of high intensity and I didn't miss a word Joey just said on that great rerun of Friends.
You can do this "commercial intervals" using any cardio machine really, so try it out and let me know what you think.