I kept waiting for it to be the worst pain -- and it never happened. Heck, I kept waiting for it to be as bad as my worst menstrual cramps. And when that happened, it turned out that was transition. With that labor, once my water broke and the urge to push kicked in, it wasn't pain, just work - like being in gym class and having to to situps for 10 minutes for the Presidential Physical Fitness testing.
2nd birth, I was waiting for it to even get as bad as the first. Sitting in the tub, hands and knees, felt a couple contractions that made me think "whooee" and suddenly my water broke and she crowned.
My appendicitis scare in high school was far, far more painful. A ruptured ovarian cyst was WAY more painful. Labor was more like a vigourous workout while having a really bad period.