The stranger moving their bag has made a shared journey easier without an introduction.

Public space runs on small unspoken cooperations. A bag lifted off a seat, a step sideways, a hand on a door: these are decisions made by people who will never speak to each other and will not remember it by evening. Most of what makes a crowded place bearable is this constant low-level courtesy that nobody records.

Do one of these deliberately today rather than only when prompted. Move before you are asked. And when someone does it for you, catch their eye and say thank you, because the acknowledgement is what keeps the habit alive in a place.