Motions of all sorts can be understood as struggles between competing mechanical factors. One mechanical quantity impels motion while the other impedes it. For each pair of mechanical quantities the roles are assigned by their relative dimensions. However, a quantity can be impelling motion in one context and impeding it in another. This episode is dedicated to this relativity in the roles played by mechanical quantities, to the fact that no quantity is always impeding or always impelling. There are no such things as "Holy Motors". To illustrate this versatility, we will first talk about viscosity. Although the name of this quantity suggests a rather sluggish role, viscosity can find itself in the drivers' seat, for instance when it is paired with density, in the context of boundary layers. The greater the viscosity, the faster the growth of the boundary layers. Another example of great historical significance is the mass itself. The mass was originally understood as inertial, as the paradigm of the impeding factor. That was until it was realized that the mass could also be the source of motion, in the context of gravity.