Signs of the times

Every day I walk to work, probably at less than 4.2mph. Today I was passing the corner of the square, when I happened upon a postwoman, who was standing with her trolley full of letters of all shapes and sizes. Up comes a man, clearly a friend as he addresses her by name, who asks: 'So how fast are you walking then?' I continued, but wondered if the postwoman had then to run to balance out that moment of stillness and meet Royal Mail targets?