In 1818, engineer William Cubitt visited a British jail, where he was horrified to find that prisoners just lounged around in the yard all day. Cubitt set to work devising a machine that would keep the prisoners occupied, and he came up with a device that required the prisoners to step onto rotating blades, which in turn would grind corn or release water. The guards at the jail were pleased that the prisoners labored in such a monotonous, degrading way [source: Roth]. Soon, this device was in every prison. Now, that machine is in every fitness club and gym.
Cubitt is credited with introducing the first modern treadmill, though its design has been tweaked over the years. Still, there are likely some gym rats that dread their turn on the contraption much as those early prisoners did. Tired of running and getting nowhere? These days, there are many workouts that you're likely to find more interesting and innovative than the treadmill.