Give me one instruction that never changes and I will not break it

The thing that works for me is a single instruction that never changes. Not a list, not a schedule that gets revised, one rule that operates every day regardless of circumstances. In three arrangements over seven years the rule has been different every time and the effect on me has been identical.

The best one was that I sent a particular short message at the same time every morning, without variation, whether or not there was anything to say, and whether or not she read it. Two years of that. I never missed one, including a week when I was in hospital and had to ask a nurse for my phone.

Forty, Manhattan, seven years in. What the fixed rule does, which no amount of occasional attention does, is put another person into every single day rather than into the days we happen to see each other.

So that is what I am asking for. One thing, permanent, non negotiable, and preferably slightly inconvenient, because the inconvenience is what makes it mean anything. Around it I am happy to be useful in more ordinary ways: errands, admin, cooking, anything practical. But the rule is the part I actually want.

Not looking for anything sexual. Not looking for occasional arrangements or anything that has to be scheduled fresh each time. And not looking for a rule that gets suspended when somebody is busy, because a rule that can be suspended is a preference.