Physical Danger
They're pretty big on safety in this job, but industrial accidents do happen. The best thing to do to avoid being a liability is 1) become well trained and 2) remain confident and alert at all times. Even when you're not driving, you've got to look both ways before you cross the warehouse floor.
There's a decent amount of physical exercise in this job—walking, picking things up, and putting them down—that sort of thing. Of course, you've still got to watch out for the dangers of a sedentary lifestyle while you're behind the wheel.