1. A method, comprising: receiving input VR imagery; extracting global motions as represented in the input VR imagery relative to a viewer of a virtual reality (VR) application; applying a dampening factor to the global motions to generate dampened global motions; generating, based on the input VR imagery and the dampened global motions, VR imagery to be rendered to the viewer at a time point, wherein generating the VR imagery further comprises: receiving one or more physiological monitoring indicators from the viewer up to a first time point; determining, based at least in part on the one or more physiological monitoring indicators from the viewer up to the first time point, the dampening factor to be applied to relative motions between the viewer and VR imagery to be rendered to the viewer at the time point no earlier than the first time point, the dampening factor being determined in a predictive model that comprises (1) a dynamics model that relates the viewer's previous queasiness states to the viewer's current queasiness state and (2) an observation model that relates the viewer's physiological monitoring indicators to the viewer's queasiness state, wherein the predictive model is implemented with an estimator that estimates or predicts the viewer's future queasiness state and an optimal controller that determines an optimal value for the dampening factor to control the viewer's future queasiness state below a threshold specific to the viewer; and generating the VR imagery to be rendered to the viewer with the relative motions dampened in accordance with the dampening factor determined in the predictive model, wherein the method is performed by one or more computing devices.