Birchbox wants its customers to try more makeup and skincare items, or possibly just spend more time on makeup and skincare. To do this, they regularly send many small sample sizes of items, so people can try them, without committing to buying a whole product. They also make people more invested in their skincare, because they allow consumers to customize their boxes. Their regular emails serve as prompts to increase motivation to use the products and build excitement for the arrival of the box. The fact that the box also comes right to your door also decreases the effort it takes to try new makeup, or even just buy makeup in general.