B.G 2.15

यं हि न व्यथयन्त्येते पुरुषं पुरुषर्षभ। समदुःखसुखं धीरं सोऽमृतत्वाय कल्पते ॥ २-१५॥

yaṁ hi na vyathayantyētē puruṣaṁ puruṣarṣabha। samaduḥkhasukhaṁ dhīraṁ sō'mr̥tatvāya kalpatē ॥ 2-15॥

yaṁ hi = = one who certainly is; na vyathayantyētē = = not tormented, who reacts; puruṣaṁ = that person; puruṣarṣabha = = O chief of men; samaduḥkhasukhaṁ = = with equanimity to pain and pleasure; dhīraṁ = brave; sō'mr̥tatvāya = he, for salvation; kalpatē = = is fit.

O Chief of men, that brave person who is not tormented by these, and who reacts with equanimity to pain and pleasure, becomes fit for salvation.

Gīta Bhāshya 2.15

By bravery one can learn to react with equanimity.

अतः प्रयोजनमाह यं हि इति॥ यम् एते मात्रास्पर्शा न व्यथयन्ति। पुरि शयमेव सन्तम्। शरीरसम्बन्धाभावे सर्वेषामपि व्यथाभावात् पुरुषम् इति विशेषणम्। कथं न व्यथयन्ति? समदुःखसुखत्वात्। तत्कथम्? धैर्येण ॥ १५ ॥

ataḥ prayōjanamāha yaṁ hi iti॥ yam ētē mātrāsparśā na vyathayanti। puri śayamēva santam। śarīrasambandhābhāvē sarvēṣāmapi vyathābhāvāt puruṣam iti viśēṣaṇam। kathaṁ na vyathayanti? samaduḥkhasukhatvāt। tatkatham? dhairyēṇa ॥ 15 ॥

[ataḥ = its; prayōjanamāha = practical use is stated; yaṁ hi iti ॥ = by ‘yam hi' verse; yam ētē = one referred here is; mātrāsparśā = by contact of sensations; na vyathayanti। = who does not get perturbed; puri = in the town / or body; śayamēva = one who sleeps / who has the ability to be detached; santam । = is capable of monk, i.e, detached living; śarīrasambandhābhāvē = due to sentiment of association with body; sarvēṣāmapi = all the time; vyathābhāvāt = is perturbed; puruṣam = the word ‘purusha'; iti viśēṣaṇam । = so is the speciality; kathaṁ = how?; na vyathayanti? = is not perturbed; samaduḥkhasukhatvāt । = having equanimity towards pain and pleasure; tatkatham? = How so?; dhairyēṇa ॥ = by bravery.]

Its (overcoming self-attachment) practical use is stated by 'yam hi' verse. The person referred here is the one who does not get perturbed by the contact of sensations. Monk is the one who has the ability to sleep in the body with detachment. [Here 'Puri' means body.] Because of sentiment of association with body one who is perturbed all the time is specially called 'purusha'. How can one overcome this disturbance? Having equanimity towards pain and pleasure. How? By bravery.