There is an episode in the महाभारत‌ where Yayati expresses interest to his sons to enjoy a youthful life and asks his sons to exchange their youthful body with his old body. One of his sons, Puru, agrees and Yayati enjoys the pleasures of physical body using the youthful body of Puru. After a few years, he comes to a realization that desires (काम) are insatiable. The nature of this realization is given in the श्लोक below. After this realization dawns on him, he returns the youthful body back to his son and leaves to the forest for meditation. The event of Yayati’s realization also comes up in the श्रीमद्भागवतम् – what is given below is an extract of this event from महाभारत‌.

न जातु काम: कामनाम् उपभोगेन शाम्यति। हविषा कृष्णवर्त्मेव भूय‌ एवाभिवर्धते।।

“One’s desires are never satiated with enjoyments”. On the other hand, with indulgence, they flame up just as the अग्नि flares up with ghee poured into it.

पृथिव्यी‌ रत्नसम्पूर्णा हिरण्यं पशव: स्त्रिय:। नालमेकस्य तत् सर्वम् इति मत्वा शमं व्रजेत्।।

Even when one enjoys the whole Earth with its wealth, its diamonds, gold and animals, and women, still his desires will never be satiated.

यदा‌ न कुरुते पापं सर्वभूतेषु कर्हिचित्। कर्मणा मनसा वाचा ब्रह्म सम्पद्यते तदा।।

It is only when a man does not commit पापकर्म in thought, deed or word in respect of any living creature, it is then that he attains the purity of ब्रह्म

यदा चायं न बिभेति यदा चास्मान्न बिभ्यति। यदा नेच्छति न द्वेष्टि ब्रह्म सम्पद्यते तदा।।

When a man fears nothing and when he is feared by none, when he desires for nothing and when he injures none, it is then that he attains the purity of ब्रह्म

इत्यवेक्ष्य महाप्राज्ञ: कामानां फल्गुतां नृप। समाधाय मनो बुद्ध्या प्रत्यगृह्णाज्जरां सुतात्।।

The greatly wise king, seeing this and having been satisfied that one desires are never satiated, received back his old age from his son (Puru).

Source:

Translation of Mahabharata by MN Dutt