न हि देहभृता शक्यं त्यक्तुं कर्माण्यशेषतः ।
यस्तु कर्मफलत्यागी स त्यागीत्यभिधीयते ॥ १८.११ ॥

na hi deha-bhṛtā śakyam tyaktum karmāṇy-aśeṣata: |
yas-tu karma-phala-tyāgī sa tyāgīty-abhidhīyate || 18.11 ||

While sāttvika-tyāga (renunciation in the knowledge level) should be the sole focus of the seeker, Krishna emphasizes that karma-tyāga (renunciation of actions) is impossible by its very nature. This is another singular concept of the dialogue:

For the embodied, it is not possible to renounce activities in full. One renouncing fruits of actions is considered a renunciate.

For any embodied one, to think of abandoning actions as such is wrong. For, such a step is not possible in the scheme of creation. This is a point already stressed earlier (3.5). As a summary statement, here Krishna re-emphasizes it.

He, who renounces the pleasant and unpleasant results of karmas, alone is a renunciate. Only such renunciation or abandonment will conduce to spiritual freedom and felicity. Whatever is done without knowing this Truth will only be a delusion. Even if it is an austere effort, it will be a sheer struggle.