I went my usual 30 minutes on the cross trainer, but I upped the resistance to 5 on the flat and 8 on the top of the hilly course. I still managed to crank out 2.3 miles on the meter and over 400 calories. I followed with 30 minutes on the treadmill and did gental hills at close to a 4 mph pace which got me to 1.9 miles in 30 minutes for another 300 some calories burned. The sweat did runneth down my face and into my eyes! Right now, I feel pretty good, but we'll see how I'm doing in the morning! :-) My back didn't hurt near as much tonight. I think it's a balance thing. As I was getting into the swing of things and tried to use my arms more, I guess it put less strain on my back muscles! I can feel the difference in my arms right about now.