Hi Sugahorse,

I am therapy now for trauma, but when I was in highschool and college I had a period of depression - about 3-4 years.

I think when depression goes on for a long time, it can negatively affect a person's self esteem and core beliefs. I know that was the case for me, and even when I wasn't so depressed anymore, I felt lousy about myself. It took a long time for me to finally feel good about myself again. (and then the trauma/SA happened - blah).

Therapy is a good place to work on changing the core beliefs because therapists see us objectively and can help us learn to draw upon our strengths.
I think it takes a really long time, though.