Making our mantra recitation powerfully primarily comes down to a mental recognition that the nature of the mantras is our inner winds. When we engage in body mandala meditations, we recognize each of the deities as being by nature our subtle channels and drops appearing in the aspect of the deities of the body mandala. Just as gold appears as coins, our channels and drops appear as the deities of the body mandala. This recognition functions to cause the deities to mix into our channels and drops which purifies them. Wherever you imagine a Buddha, a Buddha actually goes and performs their function.

In exactly the same way, we mentally recognize the mantras as by nature our inner winds. Mantras are subtle emanations of Buddhas. Wherever you imagine a Buddha, a Buddha actually goes and performs their function. By maintaining this recognition, subtle emanations become one with our inner winds just as happens in our body mandala meditations, and this functions to purify them at a very deep level.

How deeply this purification goes depends upon at what level we are engaging in the mantra recitation. There are three main ways we engage in mantra recitation – verbal, mental, and vajra. Roughly speaking, we can say that verbal recitation purifies our gross inner winds, mental recitation purifies our subtle inner winds, and vajra recitation purifies our very subtle inner winds. Vajra recitation is supreme. Here, we imagine our guru is reciting the mantra in our mind for us, like performing some sort of spiritual surgery on us, and we are basically hearing him do so. We take everything we know about relying upon the guru’s mind alone and activating the inner spiritual guide and bring that into our mantra recitation.

The important thing to know about winds is winds are the mounts for minds. If the winds are impure, the minds will be impure; if the winds are pure, the minds will be pure. If we purify our root and branch winds, we purify all our minds.

Most of our tantric practices are fundamentally about gaining control of our inner winds, with the goal of being able to gather them into our indestructible drop, absorb them into the seed letter/our root mind in the center of that, and ultimately dissolve them into the clear light. When we do, all the waves of samsara subside and we are left with the completely still, clear, and empty ocean of the Dharmakaya. This is the foundation for all Mahamudra meditations and ultimately all transfers of consciousness (of ourself or others) to the pure land.

The power of our mantra recitation – well really the power of any of our Dharma practices – depends upon four things. First, the degree of our faith that the mantras are subtle emanations of the deity coursing through our mind mixed inseparably with our inner winds, purifying them at a very deep level. Second, the purity of our motivation in reciting the mantra, ideally bodhichitta. Third, the extent of our single-pointed concentration as we recite the mantra. And fourth, the thoroughness with which we combine all of this with an understanding of emptiness. In other words, we bring the entire Lamrim into our mantra recitation.

We can also do all of this for the benefit of others, such as our family or loved ones, imagining that the mantras are entering into their inner winds, purifying them, etc.

We can read more about all of this in Tantric Grounds and Paths. There is a very extensive section on inner winds, mantras, etc., which explains everything. When doing mantra counting retreats or even in our daily practice of mantra recitation, that section is our root text.