Thanks all. Thin4good: The treadmill requires input of age and weight, and does measure the heart rate. Losingformywedding: the treadmill I use doesn't go by percentages incline wise. There are levels 1-20. I've been doing level 9 and 10. And it seems when I try to do 20 minutes on this, 20 on that, I don't burn as many calories, I get tired more quickly and I don't lose weight for some reason. That's why I switched things up to do one or two things during workouts (except for my weights/cardio days).
I don't know why, but the elliptical kicks my arse seriously. After 10 minutes on it I feel like I'm about ready to fall out. I need to work up my time on the elliptical.