What is sedentary knowledge worker energy?

Sedentary knowledge worker energy is a concept in personal epistemology: Physical activity increases available energy rather than depleting it.

Example: You have been sitting at your desk for six hours. You skipped your morning walk because you had too much to do. By 2 PM you are foggy, irritable, and rereading the same paragraph for the fourth time. You tell yourself you cannot afford to take a break — the deadline is tomorrow. So you stay seated, drink another coffee, and force yourself to keep staring at the screen. By 4 PM you have produced almost nothing of value. The next day, facing an identical workload, you force yourself out the door for a ten-minute walk at noon despite the same deadline pressure. When you sit back down, the paragraph that defeated you yesterday resolves in minutes. You write more in the next ninety minutes than you wrote in the entire previous afternoon. The walk did not cost you time. The sitting cost you output.

This concept is part of Phase 36 (Energy Management) in the How to Think curriculum, which builds the epistemic infrastructure for energy management.