I"m always, always, always in the back of the pack, so all I can offer you is what NOT to do.

I can ride forever. Hour after hour. However I am slooooow. So, just putting in hours on the bike without a serious effort will not make you faster by itself. I mistakenly thought it would. It doesn't. You (okay, I!) really need to push. Be it intervals over my long distance rides, or instead of making a goal of doing a century just for the sake of doing a century, I think I need to concentrate on doing shorter, but faster rides. In fact, that's my goal this spring.

Again, I don't know if it will work, I just know what didn't work.