I greet strangers with kindness and affection.

Strangers are the low-difficulty setting, and there is no shame in starting there. No history, no unresolved argument from 2019, nothing at stake if it goes oddly. Ten seconds of warmth for a man walking a dog costs almost nothing to produce.

That is exactly why it is worth practising on. Warmth is a muscle and it stiffens. People who can be easy and open with whoever is behind the counter tend to become, over time, slightly better at it with the ones who are harder to be warm to - the people they live with, who have earned some patience and rarely get the first draft of it.