The smell of woodsmoke on a clear winters day.
It means working outside, doing something with trees, on one of those wonderful days when the sun tries to come out, and the air is still, and you know you'll be working out here until sunset or so, and the kettle by the fire is just about boiling for tea.

And then you can head home properly tired, and have a hot shower and hot soup, Hot anything in fact, and collapse in front of a fire of the logs you cut last year