Anapanasati (Forced Breathing)

One should not resort to controlled or forced breathing as this practice is Pranayama one of the contemporary practices the Buddha tried and rejected in favour of Anapanasatti.

In Anapanasatti one just watchers the breath.

Sammā Diṭṭhi Sutta lists 16 alternatives:

I. Karma (kamma): the unwholesome [§4]; the roots of the unwholesome [§5]; the wholesome [6]; the roots of the wholesome [§7].

II. Food (āhāra) [§10], arises and ends with craving (taṇhā) [§11].

III. Suffering (dukkha) [§§14-19].

IV. Decay and death (jarā,maraṇā) [§§21-23].

V. Birth (jāti) [§§25-26].

VI. Existence (bhava) [§§29-31].

VII. Clinging (upādāna) [§§33-35].

VIII. Craving (taṇhā) [§§37-39].

IX. Feelings (vedanā) [§§41-43].

X. Contact (phassa) [§§45-47].

XI. The 6 sense-bases (saḷāyatana) [§§49-51].

XII. Name and form (nāma,rūpa) [§§53-55].

XIII. Consciousness (viññāṇa) [§§57-59].

XIV. Formations (saṅkhāra) [§§61-63].

XV. Ignorance (avijjā) [§§65-67].

XVI. Mental influxes (āsavā) [§§69-71].

Is the breath all important?

You can use the alternative object, such as a living being of Mettā meditation, however, the recommend object for the beginner from the elder Thai, such as Mun Bhuridatto, and Burmese monks, such as Ledi sayadaw or Ācinna sayadaw, is Ānāpānassati. Why?

Because the Buddha taught Dhamma sequentially, and the Ānāpānassati is the first meditation in MahāSatipaṭṭhānaSutta, KāyagatāsatiSutta, and ĀnāpānassatiSutta. Why?

Because Ānāpānassati is the easiest meditation because the breath is urging the practitioner every time while the other meditation is not. It likes someone who provoking the practitioner every moment at the nose.

I know that the breath conditions the body, in that the breath tranquilizes the body, but often I read about NOT volitionally breathing in and out and this is exactly what I am doing.

It's not that natural. It's just practicing to know the claiming down breath. The practitioner knows only breath. Don't care of volitionally or not. If you breath volitionally but you don't care of it, then you come back to know your breath, it's ok.

This is the misunderstood from the reading study system.

There are 4 subjects that the practitioner needs to recite and memorize:

1. Measuring the breathing in/out long at the apparent measuring on the nose point (sometime left hole, sometime right, sometime on the upper lip, etc, whatever is ok because the practitioner is caring to measure the breath, not the touching).
2. Measuring the breathing in/out short at the apparent measuring on the nose point.
3. Trying to measure the entire breath in/out sensitively continuously at the apparent measuring on the nose point.
4. Trying to measure the entire claiming-down breath in/out sensitively continuously at the apparent measuring on the nose point.

These 4 subjects need to go together, but the practitioner who just read without reciting and memorizing will forget some of them then the meditation will not grow upper step.

Can I use an alternative object or even open monitorin, that is many objects in a succession?

Actually, the practitioner uses many meditations in daily life as the support meditations, but the Ānapānassati is the easiest primary meditation for the beginner.

When it comes to breathing, think of it as a cyclic biorhythm more than just vacuum imposed gaseous exchange. If you chart the resting breath it would look something like cos or sin on a graph... Along with your breath there are various other biorhythms in a state of harmony and as such the functions of the body run by the background processors of the mind.

When you exercise, that strain imposed on on system results in a disharmony and in order to maintain that state of strain your mind has to exert more conscious energy on the relative harmony of the biorhythms.

As explained in my reply to this similar question: https://buddhism.stackexchange.com/a/43689/20365

A biorhythm may be encompassed by another if the agonist component (muscle - in this case the diaphragm) is turned into a passive. In other the words, by the diaphragm remaining stationary and other muscles exert enough pressure on the lungs to promote gaseous exchange, you don't have to thing about the breath, only the movement.

I got the idea from great whites and their necessity to continue swimming. They compress one side of their body so the other side of the body can be flooded with blood. Turns out we can copy their example of blood pressure efficiency for breathing efficiency when exercising.

Cultivate in harmony

Although I understand the point of view of the individual that came before me, I believe the importance of what you focus on depends on what type of practice you are working on.

You stated that "the breath conditions the body". If you are working up your concentration abilities through samatha meditation, voluntarily breathing is not an issue. Your focus should be on how long you can hold your attention onto the breath. If you notice other experiences, or thoughts arising, simply acknowledge it and return your attention to the sensations of your breath.

You may experience thoughts about your experience of breathing. The previous writer is correct in that thinking cannot observe breathing. But what the Buddha taught is that consciousness is an illusion created by a belief in a separate, permanent self. Consciousness is not self. When you concentrate on the sensations of the breath, try to observe and realize the truth that in that moment, all you are experiencing is breath. There is no one to do the observing.

You do not force to do anapanasathi meditation. Only you have to concentration your inhale and exhale pattern. Before you do that, you can concentration on any object.I think that is the beginning to start a anapanasathi meditation.

The breathing naturally arises as a "sign" that the mind has right mindfulness & right concentration. If a meditator aspires to fulfill the 16 stages of Anapansati, they should never seek to observe the breathing & never be concerned about the breathing. The Buddha taught his path is the abandoning of craving. The meditator should only watch the mind; to ensure the mind is free from craving.

An analogy is a mother hen sitting on eggs hoping for the eggs to hatch. All the mother hen does is sit on the eggs, to keep the eggs warm & safe. In time, the chicks inside the eggs will hatch the eggs. The mother hen does not use a hammer or her beak to crack open the eggs.

Similarly, the more the mind thinks about watching breathing, the less the mind will watch the breathing. This is because thinking cannot watch breathing because what watches breathing is consciousness.

Using thinking to watch breathing is the same as a mother hen using her beak to crack open the eggs. It is the wrong method & will only harm the chicks.