Physical Capacity Often Changes Before Appearance Does
You usually notice it in motion.
A pause on the stairs.
Grocery bags that need to be set down halfway to the kitchen.
The small thought, before standing up from the floor, of where your hand will go.
You don't need a dramatic before-and-after to feel it. Nothing in the mirror has changed enough to explain it. That is the point.
Capacity often shifts before appearance does, and the day is where it first becomes visible.