Bhagavad Gita, Chapter 18, Verse 9

When obligatory work is performed, O Arjuna, only because it ought to be done, leaving attachment and fruit, such relinquishment is regarded as Sâttvika.

The real difference finally gets stated plainly here, keep doing the duty, just let go of the attachment.

Krishna doesn't ask Arjun to stop acting, he asks for a real, internal shift while the actual work continues. Goodness is defined by what changes inside, not by what stops happening outside.