But (tu), now (idānīṁ), let’s hear (śṛṇu) from Krishna (me) about the three kinds of (tri-vidhaṁ) happiness (sukhaṁ) one enjoys (ramate) in (yatra) practice (abhyāsād), and (ca) reaches (nigacchati) the end of distress (duḥkhāntaṁ). (BG 18.36) Krishna finally delineates the experience of happiness in three modes that a performer of action goes through before, during, and after performing the action.

That (tad) which (yat) is just like poison (viṣam iva) at the beginning (agre) and like nectar (amṛtopamam) at the end (pariṇāme) that happiness (tat sukhaṁ) is said to be (proktam) in the mode of goodness (sāttvikaṁ). It is born of self-discernment and mercy (ātma-buddhi-prasāda-jam). (BG 18.37)

The (tad) happiness (sukhaṁ) from the contact of the senses with their objects (viṣayendriya-saṁyogād), which (yat) appears like nectar (amṛtopamam) at the beginning (agre) but like poison (viṣam iva) at the end (pariṇāme), that (tat) is considered to be (smṛtam) in the mode of passion (rājasaṁ). (BG 18.38)

And (ca), that (tat) happiness (sukhaṁ), which (yad) deludes the soul (mohanam ātmanaḥ) at the beginning (agre) and at the end (anubandhe ca), arising from (utthaṁ) sleep, laziness and madness (nidrālasya-pramāda) is said to be (udāhṛtam) in the mode of darkness (tāmasam). (BG 18.39)