BG 6.4

A person is said to be elevated in yoga when, having renounced all material desires, he neither acts for sense gratification nor engages in fruitive activities.

6.4. When, a person indulges himself neither in what is desired by the senses nor in the actions [for it], then [alone], being a man renouncing all intentions, he is said to have mounted on the Yoga.

6.4 When a man renounces even the thought of initiating action, when he is not interested in sense objects or any results which may flow from his acts, then in truth he understands spirituality.

6.4 Yada etc. What is desired by the senses : Objects of senses. The actions for them : actions such as earning the objects and so on. In this [path of] knowledge one should be necessarily attentive. This [the Lord] says-

6.4 When this Yogin, because of his natural disposition to the experience of the self, loses attachment, i.e., gets detached from sense-objects, i.e., things other than the self, and actions associated with them - then he has abandoned all desires and is said to have climbed the heights of Yoga. Therefore, for one wishing to climb to Yoga, but is still disposed to the experience of the sense-objects, Karma Yoga consisting of the practice of detachment to these objects, becomes the cause for success in Yoga. Therefore one who wishes to climb to Yoga must perform Karma Yoga consisting in the practice of detachment from sense-objects. Sri Krsna further elucidates the same:

6.4 Hi, verily; yada, when; a yogi who is concentrating his mind, sarva-sankalpa-sannyasi, who has given up thought about everything-who is apt to give up (sannyasa) all (sarva) thoughts (sankalpa) which are the causes of desire, for things here and hereafter; na anusajjate, does not become attached, i.e. does not hold the idea that they have to be done by him; indriya-arthesu, with regard to sense-objects like sound etc.; and karmasu, with regard to actions-nitya, naimittika, kamya and nisiddha (prohibited) because of the absence of the idea of their utility; tada, then, at that time; ucyate, he is said to be; yoga-arudhah, established in Yoga, i.e. he is said to have attained to Yoga. From the expression, 'one who has given up thought about eveything', it follows that one has to renounce all desires and all actions, for all desires have thoughts as their source. This accords with such Smrti texts as: 'Verily, desire has thought as its source. Sacrifices arise from thoughts' (Ma. Sm. 2.3); 'O Desire, I know your source. You surely spring from thought. I shall not think of you. So you will not arise in me' (Mbh. Sa. 177.25). And when one gives up all desires, renunciation of all actions becomes accomplished. This agrees with such Upanisadic texts as, '(This self is identified with desire alone.) What it desires, it resolves; what it resolves, it works out' (Br. 4.4.5); and also such Smrti texts as, 'Whatever actions a man does, all that is the effect of desire itself' (Ma. Sm. 2.4). It accords with reason also. For, when all thoughts are renounced, no one can even move a little. So, by the expression, 'one who has given up thought about everything', the Lord makes one renounced all desires and all actions. When one is thus established in Yoga, then by that very fact one's self becomes uplifted by oneself from the worldly state which is replete with evils. Hence,

6.4 For, when one loses attachment for the things of the senses and to actions, then has the abandoned all desires and is said to have climbed the heights of Yoga.

6.4 Verily, [Verily: This word emphasizes the fact that, since attachment to sense objects like sound etc. and to actions is an obstacle in the path of Yoga, therefore the removal of that obstruction is the means to its attainment.] when a man who has given up thought about everything does not get attached to sense-objects or acitons, he is then said to be established in Yoga.