Why is it so hard to promote my own writing?

I seem to have a mental block when it comes to my own writing; I simply don't have the self-promotion gene. My book, What You Need to Know to Be a Pro; The Start-up Business Guide for Publishers, will launch next month, but I haven't done a blessed thing to market that book. I should have sent out press releases and marketing materials to reviewers and bookstores MONTHS ago. I haven't even ordered postcards yet! I sent one letter to our local bookstore about hosting a reading, but I still haven'