ईश्वरः सर्वभूतानां हृद्देशेऽर्जुन तिष्ठति।भ्रामयन्सर्वभूतानि यन्त्रारूढानि मायया॥
īśvaraḥ sarva-bhūtānāṃ hṛd-deśe ‘rjuna tiṣṭhatibhrāmayan sarva-bhūtāni yantrārūḍhāni māyayā
Word by word
The verse says
The lord sits in the heart of every being, Arjuna, and by his power he turns them all about, as though they were mounted on a machine.
In plain words
An image that has unsettled readers for a very long time.
All beings mounted on a yantra, a machine, and turned. And the one turning them is seated in the heart of each.
It sounds like it removes everything. Two verses later Krishna will tell Arjuna to do as he likes, so whatever this means, it is not that.
Where you've felt this · in creative work
A potter's wheel turns and the pot rises under her hands. The wheel is not making the pot. She could not make it without the wheel. Neither of them produced that shape alone, and there is no way of dividing the credit that makes any sense.
Going deeper
A machine image placed four verses before an explicit handing over of the choice is the puzzle here, and the puzzle is deliberate.
Taken alone this verse says everything is driven. Taken alongside 18.63, which tells Arjuna to act exactly as he wishes, it cannot mean that. The traditions have spent a long time on this and have not agreed, which is itself worth knowing.
What the image does establish is location. The one turning things is not outside, operating the world from a distance. He is seated in the heart of each being, which means the power at work is not foreign to you and is not opposed to you.
For a reader the honest position is to hold both halves without resolving them. You are carried by something you did not set in motion, and you are about to be told the decision is yours. Most people recognise both from experience long before they can reconcile them.