We enjoy first-person authority with respect to a certain class of actions: for these actions, we know what we are doing just because we are doing it. This paper first formulates an epistemological principle that captures this authority in terms of trying to act in a way that one has the capacity to act. It then considers a case of effortful action – running a middle distance race – that threatens this principle. And proposes the solution of changing the metaphysics (...) of action: one can keep hold of the idea that we have first-person authority over what we are doing by adopting a disjunctive account of action. (shrink)