A portable electronic device monitors the pulse or electrocardiogram of a person by integrated, attachable or wireless sensors. The portable device evaluates this data in real-time to assess heart rate variability coherence, and provide feedback through a variety of sounds and an array of LEDs. The feedback may be in the form of a breathing indicator or pacer usable as a respiratory cycle training system to indicate to the subject when the next breath should be taken. Such feedback may be correlated to the level of coherency the subject achieves. A coherence indicator may be used to provide the subject with real-time information relating to the level of coherence achieved.
