Treadmills and Kids

I was lucky to learn a lesson yesterday w/o incident. I've always thought that I made it nearly impossible for the kids to start the treadmill by themselves, but I hadn't changed the way I did that now that the kids are older and smarter. In order to use the mill a person in my house would need to plug it into an outlet, turn a switch near the bottom, put the magnet piece on the dashboard and then press a number for the speed. Realizing that 3 of the 4 were always possible we hid or put the magnet out of reach.
Yesterday afternoon we heard a noise that sounded like the treadmill, went into the room where it is and Riley was on the mill at 24% grade and 4 mph! Maureen put her hand on his back and said "what are you doing?" Riley answered with "I'm doing 5 minutes walk, then 5 minutes Run." the same training I did the day before. We found out that Riley just took a magnet from the refrigerator and substituded it for the one that came with the treadmill and was hidden. At 4mph it would not been long before he was off the back of the mill with an injury if he hadn't been able to stop it before he couldn't keep up any longer. Maureen and I both learned that with the mill inside now we need to be even more careful about treamill safety.