To interact with the external world, incoming sensory information informs us about situational changes that are of relevance to our behavior and we act upon these accordingly, be it in a produced movement or an internal reaction (e.g. an emotion, paying attention). Humans efficiently interact with their world and each other and to do this, a system is required to promote relevant sensory feedback to allow fast, accurate, and appropriate actions. We review findings from single unit recordings of muscle afferents that demonstrate the effects of the descending γ-fusimotor system on their activity. This includes changes in firing from cognitive and emotional influences, which we postulate can prepare the body for responsive and appropriate action to a change in environment.