By regulating the thoughts or by regulating the breath, it is impossible to get Self-realization.+

Kena Upanishad (9)- Chapter I -That which cannot be smelt by the breath, but by which the breath smells an object-That alone know as Brahman, and not that which people here worship.

Sage Sankara:~  The vital- air-Sheath cannot be the Self because it is the modification of air (Vayu). Like air, it enters the body and goes out of it never knowing the joy and sorrow like others. It is ever dependent on the Self.  ~VC~165-166

Breath, body, and the world are one in essence. That essence is formless consciousness.   The Soul, which is present in the form of consciousness is the innermost Self.  Breath, body, and the world are part and parcel of the illusion. By holding the breath (vital force) as the Self, one cannot get rid of the ignorance. Without getting rid of ignorance wisdom will not dawn. Wisdom dawns only when one realizes the form, time and space are one in essence.

The 'Self' does not breathe because it is formless. The Self is not a thinker because it is ever formless, timeless, and spaceless. By regulating the thoughts or by regulating the breath, it is impossible to get Self-realization. 

The Self is not the thinks and the one which breaths. You are the thinker. You are the breather. The Self is not you, but the Self is the one which witnesses you and the world together. Therefore, it is erroneous to say ‘I AM THIS’ or ‘I AM THAT’ because the ‘I’ itself is an illusion. Thus, it is necessary to know ‘What is ‘I’? to realize the truth beyond form, time, and space.

Remember:~ 

If you are caught in the grip of the ‘I’ then you will remain permanently in the grip of ignorance. If you hold the Self as ‘I’ you will never be able to cross the dualistic illusion.    If you follow the ‘I’ based teaching it is like the blind leading the blind

If you inquire   “Who am ‘I’?  the ‘I’ will not disappear. You must know the nature of the ‘I’, which appears and disappears.

The Soul is the witness of the ‘I’ which is permeant and eternal. The Soul is the subject and the ‘I’ is an object.

The ‘I’ hides the Soul. Therefore, the seeker has to realize ‘what is this ‘I’ supposed to be in actuality

If the Self is not ‘I’ but the Self is the Soul then from the standpoint of the Soul, the Self: ~

Where is the ‘I’?

Where is the ego?

Where is the body?

Where is the mind?

Where is the world in which you exist?

Where are the form, time, and space?

Where is the waking experience?

Where is the duality?

Where is void?

They are or have become one with the Soul which is present in the form of consciousness. The consciousness is the ultimate truth or Brahman.

The ‘I’ is present only when the mind is present. The mind is present only when the world is present. The world is present only when there is the waking experience.

Deeper self-search reveals the fact that the waking experience is not considered different from the world. The world is not considered different from the mind. The mind is not considered different from the’ I’. This truth has to be assimilated.

The ‘I’ is merely an illusion created out of the Soul, which is present in the form of consciousness. ‘I’ is not the subject. The ‘I’ is an object to the Soul, which is the formless, timeless, and spaceless subject.

If the ‘I’ is an illusion then the world in which you exist is bound to be an illusion.

If the ‘I’ is an illusion then three states, are bound to be an illusion.

If the ‘I’ is an illusion then the form, time, and space are bound to be an illusion.

If I’ is an illusion then the individual experience of birth, life, death is bound to be an illusion.

If the ‘I’ is an illusion then the words and thoughts are bound to be an illusion.

If the ‘I’ is an illusion then the duality is bound to be an illusion.

The seeker has to make sure what is this ‘I’ supposed to be? The seeker has to make sure the unreal nature of the ‘I’ which comes and goes to realize the truth, which is beyond the form, time, and space

That is why Bhagavad Gita: ~ The permanent is always there, only the transient ‘I’ comes and goes. (2.18)

The ‘I’ hides the Soul, which is the cause of the illusory universe. 

People think the ‘I’ without the body is the Self. The seeker has to understand the fact that ‘I’ is not the Self, but the witness of the ‘I’ is the true Self, which is eternal.

That is why Ashtavakra Gita 16:10:~ If you desire liberation, but you still say "I," If you feel the ‘Self’ is the ‘I’, You are not a wise man or a seeker. You are simply a man who suffers.

People are stuck with the reality of the ‘I’, which they take as real because some Gurus have propagated the Self is the ‘I’. is no need to convince such mindsets. The seeker of truth accepts only the truth nothing but the truth.  : ~ Santthosh Kumaar