I agree that variety helps with the exercise. Also, finding the best time of day for you to do it.
I would love to exercise first thing in the a.m., but since I start work at 6:00 a.m., I've started doing my workouts at 4:00 p.m. I alternate between:
Curves (3 or 4 times/week)
The Firm tapes (when I want a good cardio + strength training workout - and really want to sweat!!)
Walking on the treadmill (when I also want to watch something on TV)
I also think it's good for our bodies to have variety because our muscles don't get used to the same routine. (I think it was Covert Bailey who wrote about that.)
Nancy, Bountiful UT