Motion has traditionally been defined extrinsically, as the change in the position of an object, such as a particle, over time. In previous work titled "Motion From a Particle's Point of View: An Interpretation of the Double Slit Experiment" we argued that this definition of motion is incomplete and that it is using it which leads to the "weirdness" of quantum mechanics, as exemplified by the double slit experiment. We proposed an alternative intrinsic definition of motion, using which we claimed quantum mechanics can be understood without weirdness. In this paper, we extend this previous work, which only considered constant-speed motion of a single particle, to the case of: first, multiple particles in constant-speed motion; and, second, the case of multiple accelerating, that is, interacting, particles. We show we can in this way recover the key equations and phenomena of both special and general relativity. By showing that the intrinsic definition of motion underlies the theories of special and general relativity, as well as quantum mechanics, we propose it may be of use in developing a theory of quantum gravity.