What was Mary doing at the beginning of the dialogue?

M: Hello, Mary. Why are you standing here in the cold wind?
W: I’m waiting for a bus, but the buses are very full at this time of the day.
M: Where are you going? This isn’ t your way home. You must take a bus from the other side of the street to go home.
W: But I’ m not going home now. I’ m going for a walk in the park.
M: Going for a walk in such cold weather?
W: I always like to go for a walk before supper.