When the day went dry again

It will. A week of travel, a run of early meetings, a cold, a house move, and you'll look up on a Thursday and realise the glass hasn't been next to the cup since Monday and the headache is back at three. The question is what happens next, and the habit's survival depends on it.

The first thing is that a week off isn't the habit gone. Phillippa Lally and colleagues followed 96 volunteers building a daily habit and found that missing one opportunity didn't materially affect how the habit formed. Three or four days off will set you back a little and not to zero. The glass next to the kettle is still there and the pouring still comes back faster than it did the first time.

The second is not to make it a project again. The mistake after a lapse is to decide that this time you'll really do it, buy the bottle with the hours on it, set a reminder, and drink two litres on Friday. That's the fad, and it's what fails on the following Tuesday. The recovery is the same as the method. Next hot drink, a glass with it. Next meal, a glass on the table. Nothing to make up.

The third is to ask which chapter the lapse came from. If you stopped because of the loo, chapter 10, move the last glass earlier. If you stopped because of the fetching, chapter 11, put the glasses back where they live. If you stopped because you were somewhere with no water in sight, ask for it, because it's always there and always free. Most lapses have one cause, and it's usually one of these three and usually small.

And don't wait for pale pee before you count yourself back. The pale check is a gauge and not a judge. A dark afternoon after a dry week is information, and the answer to it is the next glass, not a verdict on you.