A full calendar can conceal an empty battery.

A packed schedule provides constant evidence that you are doing enough, which makes it easy to miss that you are running on very little. The activity itself becomes the reassurance, and nobody looks at what is underneath while the calendar still looks respectable. Emptiness of this kind can go a long way before it announces itself.

Rather than checking whether your week is full, check whether you have anything left at the end of it. Ask that question on a Thursday evening. The answer is more informative than the calendar.