Delete the prefixes and hold on to the common factor in all of them. That is Aham-’I’, that is the gist of the whole matter.

Devotee: : Is it necessary to control one’s breath? What becomes of the man who has not practised breath-control?

Ramana Maharishi: Breath-control is only an aid for diving deep. One may as well dive down by control of mind. On the mind being controlled, the breath becomes controlled automatically. One need not attempt breathcontrol; mind-control is enough. Breath-control is recommended for the man who cannot control his mind straightaway.
Naham - I am not this - corresponds to rechaka
Koham - Who am I? (search for the I) - corresponds to puraka
Soham - He am I; (The Self alone) - corresponds to kumbhaka.
So these are the functions of pranayama. Again the three formulae are:
Na - Aham (Not - I).
Ka - Aham (Who - I).
Sa - Aham (He - I).
Delete the prefixes and hold on to the common factor in all of them. That is Aham-’I’, that is the gist of the whole matter.