What is rumination cognitive cost?

Example: You spend an entire Saturday unable to relax because part of you wants to work on the side project and part of you wants to be present with your family. You do neither well. By evening you're exhausted — not from effort, but from the continuous background negotiation that never reached a resolution. The conflict consumed the energy that either activity would have used.

This concept is part of Internal Negotiation in the How to Think curriculum, which builds the epistemic infrastructure for internal negotiation.