I've used treadmills at work. Some folks love them, some folks hate them. They make me seasick.
Folks who like them seem to get a kick of motivation from watching their speed and time. You can also listen to your foot-falls to be sure you are running evenly. Working on even strides can be entertaining. Also listening for your foot-falls to be quiet (not slamming your feet down) can be entertaining. And good for you, too.
"If Americans want to live the American Dream, they should go to Denmark." - Richard Wilkinson