# You do work when you lift the pizza boxes. You do NO work ( in the physics sense ) when you carry the pizza boxes. WHY?

As work done = force x displacement parallel to the force, no work is done. (The equation in its proper form is $W = F \times s \cos \theta$ where $\theta$ is the angle between them. Cosine has the value 1 at 0 degrees, but 0 at 90 degrees, so no work is done.