The brief encounter deserves enough care that neither person has to recover from it afterward.

Short exchanges get treated as if they leave no trace, and they often leave one. A curt word at a counter takes a few seconds and can sit with someone for the rest of their shift. Brevity limits your investment, not the effect. Manners in passing are less a formality than a way of not leaving small injuries behind you.

Pay attention to the three or four minor exchanges you will have today: the driver, the neighbour, the voice on the phone. Aim to leave each one costing nobody anything to shake off.