When you were growing up, your parents or teachers probably told you to sit and stand straight, instead of slouching your back and shoulders. They themselves may not have exactly known why that was important, it just seemed that way. But more recent science has found that they were actually right in many more ways than they imagined.
Almost everyone I meet with expresses concerns about their posture. It makes total sense: we all sit way too much, and it is almost impossible to sit for long periods without becoming slightly rounded forward. For most of us some amount of sitting is a necessary evil, but that doesn't mean you can't take steps to mitigate the damages!