B.G 5.21

बाह्यस्पर्शेष्वसक्तात्मा विन्दत्यात्मनि यत् सुखम्। स ब्रह्मयोगयुक्तात्मा सुखमक्षयमश्नुते ॥२१॥

bāhyasparśeṣvasaktātmā vindatyātmani yat sukham। sa brahmayogayuktātmā sukhamakṣayamaśnute ॥21॥

[बाह्य स्पर्शेषु असक्तात्मा विन्दति आत्मनि यत् सुखम्। स ब्रह्मयोग युक्तात्मा सुखम् अक्षयम् अश्नुते॥
bāhya = external; sparśeṣu = touch (of sense organs); asaktātmā = unattached person; vindati = experiences; ātmani = in himself; yat = which; sukham = happiness;। sa = that same; brahmayoga = by the practice of Brahma; yuktātmā = engaged being; sukham = happiness; akṣayam = everlasting / increased; aśnute = attains;]

The one who is disinterested in the external engagement of sense organs, experiences within himself happiness. The person engaging in the practice of 'Brahma-Yoga' obtains the same happiness in everlasting proportion.

Gīta Tātparya 5.21

Remembering the Supreme Lord is the 'Brahma-Yōga' .

इदानीमपि परमात्मनि स्मृऽतमात्रे सुखं विन्दतीति यत् तदा स एव सम्यगुक्तः किमु ॥२१॥

idānīmapi paramātmani smr̥'tamātre sukhaṁ vindatīti yat tadā sa eva samyaguktaḥ kimu ॥21॥

[इदानीमपि (idānīmapi): Even little; परमात्मनि (paramātmani): In the Supreme Lord; स्मृऽतमात्रे (smṛ'tamātre): In the mere remembrance; सुखं (sukhaṁ): Happiness; विन्दति (vindati): Attains or experiences; इति (iti): Thus or in this way; यत् (yat): Which; तदा (tadā): Then; सः (saḥ): That person; एव (eva): Indeed/alone; सम्यग् (samyag): Rightly or accurately; उक्तः (uktaḥ): Called or said; किमु (kimu): What then?;]

When even little rememberance of the Supreme Lord indeed gives happiness, what then of those who undertake it well?