Apparatus for improving health of a user is provided, including a first sensor, adapted to measure a first physiological variable, which is indicative of a voluntary action of the user. A second sensor is adapted to measure a second physiological variable, which is substantially governed by an autonomic nervous system of the user. Circuitry is adapted to receive respective first and second sensor signals from the first and second sensors, and, responsive thereto, to generate an output signal which directs the user to modify a parameter of the voluntary action.