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॥

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.

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.