What a short walk does
After a meal, glucose from the food enters the blood, and the body has to move it into muscle. Insulin does most of that work. But contracting muscle takes up glucose on its own, without waiting for insulin to open the door, and walking puts the largest muscles you own to work at the exact moment the glucose arrives.
The result, consistent across a decade of studies, is a lower and flatter rise. The spike becomes a hill. You feel that difference as the absence of the heavy, drowsy slump that follows a big meal eaten sitting still.
Why the timing is the mechanism
Walk before the meal and you get some benefit, but far less, because the glucose is not there yet. Walk hours later and the rise has already happened. The window is the point: ten minutes starting within half an hour or so of the last bite catches the curve as it builds.
This is why the advice is so specific, and why the specifics matter. The walk is not exercise in the general, virtuous sense. It is a tool aimed at a particular twenty minutes of your physiology, and aiming it elsewhere spends it for very little.
Making it stick
Attach the walk to a meal that already happens every day. Lunch suits most people; pick dinner if that is the chaotic one. Fix the route. The same dull loop every time, so there is nothing to plan and nothing to negotiate at the door.
Leave the shoes by it, because the two minutes spent hunting for footwear is where this habit goes to die. And keep it at ten minutes. Twenty sounds more virtuous, and it is exactly the kind of upgrade that turns a daily habit into an occasional one. The meal happens anyway. The walk just has to be welded to it.
When it does not work
Rain. Dark. A bad knee. Some days the loop around the block is genuinely not happening, and fine. The fallback is anything that contracts the same large muscles under your own roof: the stairs climbed a few times, a corridor walked back and forth, marching on the spot in the kitchen while the kettle boils.
It looks ridiculous. It works on the same mechanism, and nobody has to see it. The only version that fails is the one where ten minutes becomes zero minutes because the weather was rude.
Ten minutes, after a meal you were going to eat anyway. The cheapest thing on this site, and the one with the most evidence behind it. Shoes by the door.