It's not always what you're running to, but what you're running from.
Dangle a carrot from a string in front of a donkey, and you can steer him anywhere. Why? Because donkeys are stupid. Who is that motivated at the prospect of eating a carrot? If anything, the prospect of having to eat a carrot is more motivating. That's why each one of these treadmills allows you to mount a carrot on a string directly behind you on the machine. It will serve as a constant reminder that, while exercising sucks, eating carrots sucks even more.