Question for brides with hostesses

Hi all,

I have a question regarding an upcoming wedding and am looking for advice. A college girlfriend recently announced her engagement and bridal party with me being a hostess... not being fully aware of hostess duties I accepted happily ... however in recent emails to the bridal party.. she has made it clear that this is a position in which a lot of work is required including a line which stated for 'hostesses to wear comfortable shoes becuase we will be standing all day.' ... While i recognize that this position is an 'honor' I DO NOT want to do this at all (am not the kinda girl who would even wear comfortable shoes to a wedding) and would rather just attend as a guest. The wedding is July 13, 2003. Is it too late? and how can I break this news to her?
Any advice would be appreciated.
Thanks ladies!