Dan has said that one of the things that should be done when tuning the heart, is to increase the "Left/Right" motion of the arrow in the Cepstrum screen. Doing this is supposed to increase Heart Rate Variability. Try as I might, my Coherence peaks always seemed to stay between 0.6 and 0.8Hz through most of my daily sessions, since I got the Heart Tuner last year.
Then, the other day, I began to look at the secondary peak to the right of the arrow, and wondered what would happen if I just focused my attention on this secondary peak? Sure enough! Duh!
Amazing! I consider this to be a huge breakthrough.