Worthlessness

I don't know why, but some days I just feel so worthless. I don't know why I feel like this. I can't explain my feelings to anyone, its too hard for me to do it without breaking down and crying. I feel like I get in these moods, in these deep depressions because I don't feel like anyone understands me. I just totally break down and want to block everyone and everything out. I just feel like no one will understand why I am like this. Guess I have to learn to deal with this...