Vivekachudamani 26

sarvada sthapanam buddheh suddhe brahmani sarvada |
tat sama dhana mityuktam na tu cittasya laalanam ||
(Sankaracarya's Vivekachudamani 26)

Samaadhana or one-pointedness is that condition when the mind is constantly engaged in the total contemplation of the ever-pure Brahman, and it is not gained through any curious indulgence of the mind.

Śukadeva Gosvāmī recommends by practicing yoga one changes the habit of the mind, to bring the mind under control and the next step in God-Realization, namely to fix one’s mind in the service of the Personality of Godhead.

“Anyone who does not render service and neglects his duty unto the Primeval Lord, who is the source of all living entities, will certainly fall down from his constitutional position and not fit to understand the Lord.” As soon as you come to the material world, the ahankara will cover your mind by making us to think, that "I... I belong to India." "I belong to America." "I belong to brahmana community, ksatriya...". Ahankara-vimudhatma. So long this ahankara is there, "I am this, I am that," all bodily concept and it will be hard for us to fix our mind upon Brahman.