Why NOT to be a social worker?

I am having trouble deciding if a social work career is right for me. I applied to an MSW program and didn't get accepted for fall 2011, but now I am not sure if I should apply again next year. As of right now, I don't even know what type of social work I would like to do. So I am wondering, what are some reasons that a person might not make a good social worker? What are some negative characteristics of a social work career?