A few years back I wouldn't DREAM of running on a conveyor belt but like Cathe, that all changed when the kids came along. It was not possible to run outside much anymore. Now my feet, knees and hips thank me for relieving them of the constant pounding on the concrete (although I still get sore from the treadmill.) I used to run outside no matter what but I am a wimp now-can't stand being in the cold. I couldn't run on the conveyor if I didn't have the TV in front of me with my headphones on watching all those shows I tape. It helps to have a good treadmill too, which I do.