If you're wondering why your 3-mile jog on the treadmill was so damn hard this morning, here's some insight: Treadmills were originally used to torture English prisoners.
Yes, you read that right. Back in the 1800s, prisoners in England spent hours stepping on the spokes of large paddle wheels.
The wheels served a lot of purposes -- they pumped out water, crushed grain, powered mills -- and the prisoners were forced to use them for up to six hours a day.
The many hours on the torturous treadmills had prisoners climbing up to 14,000 feet per day. That is almost halfway up Mount Everest.
Although the wheel's model was more similar to the step machine of today, its mill-powering function earned it the name "treadmill."
The treadmills were eventually banned for being way too brutal, but they reemerged in the 1900s when people realized using them could help them lose weight.
A history lesson like this is just another great reason to run outside.