Pressures at work. Worry because you can't find work. Conflicts at home. Loss, loneliness. These are just a few of life's challenges that can lead to feelings of depression, or worse. But there's a big difference between "feeling down," and true mental illness issues that need to be addressed with professional help. How can you tell if you need to seek counseling and/or treatment? Here are eight signs that you need to pay attention to.