The pair

Here's the method, and it's small enough to fit in a sentence. Every time you have a hot drink or a meal, you have a glass of water with it.

The hot drink. When you make or fetch the coffee at seven and the one at ten, you fill a glass of water at the same time and it goes where the coffee goes. You drink it whenever, before, during, after. It doesn't matter. If you're at a café, you ask for a glass of water with the coffee, which every café will give you. If someone's fetching for you, they can fetch a water too. Two coffees become four drinks, and the count for the morning is done without anyone feeling thirsty.

The meal. A glass on the table at breakfast, lunch and dinner. If you eat at your desk, a glass on the desk. If lunch is a sandwich walking between places, a bottle in the other hand. This is the easiest part, because most people already drink something with meals, and McKiernan's study found three quarters of fluid was drunk around them. The pair just makes sure the something is there and isn't a can of sugar.

The count. Two hot drinks and three meals is five glasses, plus the two coffees, which is seven drinks, which is inside the six to eight the NHS mentions, and you haven't done anything except pour. If you have a third hot drink, that's eight. Nobody's counting, and you don't have to.

The glass. One at the kettle, one at your desk, one at the table. Left out. The friction in this method is entirely in fetching a glass, so remove it once and it's gone.

Taste. Whatever you'll drink, without sugar. Tap water, sparkling, a squeeze of lemon, weak squash. Chapter 9 is the whole discussion.

Evenings. The pair stops after dinner unless you want it. If the night is a concern, the dinner glass is the last one, and a hot drink at nine goes without a partner.

That's all of it. The pair takes about a fortnight to stop feeling like an instruction, and after that the glass appears next to the cup without a decision, which is the only kind of habit that survives a busy week.