Some of our favorite smells can transform our moods instantly when they hit our nostrils.
Take the smell of coffee, for instance, or the smell of something delicious baking in an oven. With one whiff we can go from having the worst day ever to the best moment of the day.
Conversely, there are just some smells that can spoil everything. Take, for example, the smell of mildew. As someone who has lived through a flood, when I smell mildew, I just about start to cry from anxiety. I know, from experience, that that smell can mean not only that something might be ruined or destroyed, but that it's going to be a process to clean up--one that takes time and energy--and my mood is instantly brought down.