Cognitive load refers to the amount of mental effort being used in working memory at any one time. Working memory is limited — it can hold approximately 7±2 items simultaneously. When cognitive load exceeds this capacity, performance degrades.
Effective teaching reduces extraneous load so more mental capacity is available for germane load. For personal productivity: decision fatigue is accumulated cognitive load. This is why planning the next day the night before, meal planning, and laying out clothes reduce the effort of executing a day. Simplifying choices reduces cognitive overhead.