Lingerie not only helps you look beautiful and seductive, it is also functional because your breasts also need a well-fitting bra.
Breasts are composed exclusively of soft tissue: skin, mammary glands, blood vessels, fat tissue and ligaments. The ratio between these tissues change with age, but breasts do not have a muscle or a bone to protect them from gravity or other forms of extreme pressure, like sports. That is why the breasts require external support, from a well-fitting bra.
The larger the breasts, the greater the need of good support. Breasts that are inadequately supported soon loose their shape and firmness, which is not aesthetically pleasing and may be painful.