What is energy journal?

Energy journal is a concept in personal epistemology: Tracking your energy and mood on paper reveals patterns invisible from inside the experience — because you cannot optimize a signal you never measured.

Example: You feel 'tired' every afternoon and assume it's the lunch crash everyone talks about. Then you track energy on a 1-10 scale for two weeks and discover your trough actually hits at 10:30 AM — right after your recurring standup meeting — and your afternoons are a second peak. Without the external record, you would have reorganized your schedule around a pattern that didn't exist.

This concept is part of Phase 10 (Externalization Mastery) in the How to Think curriculum, which builds the epistemic infrastructure for externalization mastery.