If you're on break, as long as your walking path does not violate any plant rules, should be good.
If I were you, I would try to fit my walking into what I need to do. Take the long way around, instead of the short cut through the line area.
When I was at DuPont, our plant had a single hall way almost 1/4 mile long, and dead straight. The lab was at one end, the main office in the center, and the parking lot access at the other. My office was off a hall way about 1/3 of the way from the parking lot. You walk that a few times a day, you'd be in good shape too.
Another idea is to take the stairs instead of the freight elevator. At a pulp and paper mill that I was at, the control room was on the 3rd floor, my office across the compound in an Atco trailer. I walked that at least 4-5 times a day, in steel toe boots, Nomex, hardhat, winter coat, and some equipment.
This one really bugged the guys I car pooled with. I would park in the middle of the employee lot, closes to the exit to the road, rather than closes to the mill entrance. This way, I got some exercise, and was able to get my car out faster once I got in it.
I was in the best shape of my life when I worked in the plants/mills.