You push a cup on a table.

The cup moved because your arm hit it with force in a specific direction.

Your arm moved because of electrical signals sent to the arm.

Electrical signals were sent through the arm because of electrical signals in the brain.

Where do the electrical signals in the brain come from, why are they originated, and how are they originated (physical mechanism that triggers this chain reaction)?

Can thoughts literally pop up without without a cause? What is step one of every interaction you have with reality?