Sit on a ball in a neutral position with your stabiliser muscles activated.
Gently nod your chin as though rotating around that pivot point going through your ears without tensing your side neck muscles.
Visualise using the deeper muscles that sit behind your throat whilst keeping relaxed.
Hold this position for the required duration while continuing to breathe in a controlled manner by expanding and contracting your lower rib cage.
This is subtle exercise and takes practice to perform without activity of the side neck muscles.
These deep neck muscles are important to retrain to help headaches and neck issues from office or computer work.