When I work, I wear pants usually because I want to be comfortable. I wear dark colors, especially in winter, because I don't want to concentrate on myself but on what I'm working on. Because I really, really love clothes, I can start to think too much about myself. It's distracting.
You can wear black at any time. You can wear it at any age. You may wear it for almost any occasion; a 'little black frock' is essential to a woman's wardrobe.