Sankhya Yoga 2.15

 Verse 2.15

यं हि न व्यथयन्त्येते पुरुषं पुरुषर्षभ |

समदु:खसुखं धीरं सोऽमृतत्वाय कल्पते || 15||

yaṁ hi na vyathayantyete puruṣhaṁ puruṣharṣhabha

sama-duḥkha-sukhaṁ dhīraṁ so ’mṛitatvāya kalpate

yam—whom; hi—verily; na—not; vyathayanti—distressed; ete—these; puruṣham—person; puruṣha-ṛiṣhabha—the noblest amongst men, Arjuna; sama—equipoised; duḥkha—distress; sukham—happiness; dhīram—steady; saḥ—that person; amṛitatvāya—for liberation; kalpate—becomes eligible

O Arjuna, noblest amongst men, that person who is not affected by happiness nor distress, and remains steady in both, becomes eligible for liberation.

Sri Krishna talks titiksha as the primary eligibility for liberation. He says Only that person who is not shaken by the dualities becomes eligible for liberation. He puts titiksha as the single most important quality that one should possess. The one who has the mind with the ability of discrimination will not be shaken by pleasure or pain and is in a mental state of equanimity at all times. He knows clearly well about the fleeting and transient nature of duality and remains unaffected. He is referred to here as dheera. This same person is referred to as pandita in verse 2.11. Since he is not affected by the dual nature of things and has fixed his mind on his own self, he is said to be qualified to moksham or amritatvam.(Moksham means liberation and amritatvam means immortality.)

The best way to live this life is to apply our discriminatory power in all our experiences, realize the real nature of duality and raise ourselves to the state of dheera. This quality will take us to liberation.