Chapter V Sloka 21

baýSpzeR:vs­aTma ivNdTyaTmin yTsuom!, 
s äüyaegyuKtaTma suom]ymîute.

b˜hyasparþeÿvasakt˜tm˜ 
vindaty˜tmani yatsukham | 
sa brahmayogayukt˜tm˜ 
sukhamakÿayamaþnute ( 5|21)||

With the self unattached to external contacts he finds happiness in the Self. With the self engaged in the meditation of Brahman, he attains endless happiness.

Commentary:

When contacts with the external world through the media of the BMI (body, mind and intellect) are clipped down clean, we get ourselves awakened to the meadows of God-consciousness and come to live the joy that is the eternal nature of the Self. A seeker, having thus redeemed his own mind and intellect from their preoccupations with the external world at least during his meditation when he comes to keep his 'heart devoted to the meditation of Brahman,' attains imperishable happiness. The term 'heart' is to be understood as the collective name for the inner instruments of knowing and experiencing.

From sloka 25 onwards, Krishna explains further that such a liberated person engages himself in Lok-seva. His body, mind and intellect are offered as oblations into the sacred fires of activity. Ehile remaining at rest with himself, the saint lives on in an unbroken consciousness of the Divine, the Eternal.