Lifeguards rotate stations because attention wears out. Learn to notice when yours is fading.

Attention is a supply that runs down, not a trait you either have or lack. Nobody can watch carefully for hours, which is why lifeguards swap stations rather than relying on effort; the rotation is built around a known limit instead of a personal weakness. Fatigue arrives quietly and often feels like the work getting easier. That is usually the moment you start missing things.

Learn your own signs: rereading the same line, drifting, fidgeting. Build a change in every forty minutes, a different subject or a short walk. Switching before you fade works better than pushing through it.