It is important to note - as every yogi knows- that the biggest control we have of own emotion and meditation - is taking coherent control of the breath.
The breath is a direct pressure phase lock to both the low frequencies in the HRV
(LF -0.1hz/HF- health regulators) and spine liquid pump - and indirectly to the key signature set for the higher 7-20 hz heart frequencies which ARE the drummer for entraining the all important brainwave alpha and beta.
Since the breath IS the spine pump mechanically entrained - it bears repeating - from the cranio-sacral literature: "if the (breath coherent) spine liquid IS pumping - then it is clinically impossible to BE depressed!"
Regular Slow Breathing patterns have a direct action on the sympathetic system and on your CranioSacral liquid pump.
The best coherence in your body (and so in your breath) is when you are breathing in phase with your internal rythms.
One of the main interesting rythm inside the body is a pressure wave (Mayer wave - related also to cranio-sacral wave). This wave has a frequency about 6 times per minute (0.1Hz). But can vary around this frequency and is commonly between 5-7 cycles/minute.
When there is an inflamation inside your body, the frequency can increase (even above 10-15 cy/minute). When your body is very tired or due to tiring of some deseases, the rythm can go down below 5 cy/minute.
So this rythm will always be different according to how you feel and also there could be a small difference from one minute to the other (as your body is not a fixed matter, but a living thing). The first minute coud be 5.5 cy/min and the next one 6/min, and the next one 6.3 cy/min.
Children can more easily connect to this « ancestral » rythm. It is more difficult for adults.
So the pacer is used to help your body to recover the feeling of this rythm.
At the beginning, try with 6cy/min, but try also different paced frequencies between 5 and 7. The best coherence will be when the paced frequency is closed to your own internal rythm.
The more you will practice, the more your body will recover the feeling of the wave.
The aim of these breathing sessions is to finally get rid of the pacer and let your body create intuitively the right breathing pattern. In this case, you will not need the pacer anymore.