writer's block of an enormous sort

I need to learn how to write better. I always have this feeling that I want to write something, be it a journal entry or a meaningful blog post or that column that I keep telling Matt I'll write for the sports section of The Daily. There's always something that inspires me, but when I go to put pen to paper (fingers to keyboard, rather) my mind goes blank, and I've got no idea what to say. I try thinking of those great things I had thought about before...but the ideas have dissipated! I'm wondering if this is some inherent part of me or if I can make an attitudinal switch that will enable me to write. Maybe it's fear that's keeping me back. I guess I sometimes read other people's writing (in newspaper and magazine stories, in blogs, etc.) and think how good they are and how I wish I would have gone to journalism school. I know I'm preaching to an empty pew in this post, but I think I need some help...some motivation or some tricks?