I vary my cardio workouts - 1-2 HIIT sessions a week, rest steady state. In the nice weather, I walk a 3.5 mile "block" in our neighborhood; winter I do a mix of elliptical, treadmill and bike, usually in 15 minute segments (preventing boredom).
Katie, I often use the early weeks of Couch to 5K podcasts for my HIIT on the elliptical. Times goes faster with the music and someone telling me when to speed up and slow down works better than watching the timer. The later weeks when you are running more don't work as well since you're running longer.
The article was interesting, and I need to go back and read the backup stuff, but I think it all comes down to doing what works for yourself! Except of course, what mentally often works for me is not doing anything - and that definitely does not work for my body!