Meet the miniTREAD: a motorized under desk treadmill with 8 programs that gives you a light workout while sitting. It has adjustable incline from 8 to 14 degrees. It weighs only 24lbs, so you can easily move it around. The miniTREAD measures 19 x 20 inches.
This electric motorized treadmill has max leg load wight capacity of 80lbs. You can find out more about it here.