1. A method for delivering a vagal stimulation therapy to a vagus nerve, comprising: delivering a neural stimulation signal to non-selectively stimulate both afferent axons and efferent axons in the vagus nerve according to a predetermined schedule for the vagal stimulation therapy; selecting a value for at least one parameter for the predetermined schedule for the vagal stimulation therapy to control the neural stimulation therapy to avoid physiological habituation to the vagal stimulation therapy, the at least one parameter including at least one parameter selected from the group of parameters consisting of: a predetermined therapy duration parameter for a predetermined therapy period; and a predetermined intermittent neural stimulation parameter associated with on/off timing for the intermittent neural stimulation parameter.