I have an example. The first paragraph explains why it would not be a situation of doing work on a box, and the second would be why it WOULD. Someone explain the difference btw the two, please.

If you hold a box above your head at the same height and walk in a straight line, youre doing no work on the box bc it's at the same height (same potential energy) and when you stop walking the box is not moving so there's no kinetic energy added, either.

this makes sense to me...BUT, there's one issue. I also know that work is force*d, where force is in the direction the box traveled. If youre walking around with a box above your head, you obviously HAVE to be applying a force to the box in the direction that youre moving. so you would be doing work on the box.