Devices and methods for providing feedback on breathing rate are disclosed. The device comprises: a sensor interface configured to receive an electrocardiogram ECG signal; an ECG analysis unit configured to obtain a breathing rate from the received ECG signal; a feedback output mechanism for providing feedback; and a feedback generator configured to obtain an optimal breathing rate in accordance with a desired outcome and one or more heart rate and/or breathing rate characteristics detected from the ECG signal. The feedback generator is further configured to control the feedback output mechanism to output feedback synchronized to the optimal breathing rate, and subsequently adapt the feedback in accordance with changes in the one or more heart rate and/or breathing rate characteristics while the feedback is being outputted.