I have the same problem. I used to be like a rock in turbulence. In college I was on a flight out of MCO during some severe thunderstorms. I slept right through it, but apparently a good number of the pax lost their lunch.

Then a few years ago I was flying out of DEN and we hit some bad turbulence- the worst I've ever experienced. I've been very nervous in turbulence ever since. The best thing for me is to get my mind off of it - engage in conversation, watch a movie, read a magazine - and an occasional drink doesn't hurt either!

For me, knowing what's coming just makes it worse. In December I was flying back to DEN after the holidays and before we even took off the pilot announced mountain wave conditions in DEN. I was a wreck the entire flight. When we started our descent I prepared for the worst. We hit the slightest little bump and the pilot made a comment like "Well we knew it was going to be bumpy but we didn't think it would be THIS bumpy". What?? That was NOTHING! I had psyched myself out for nothing. That experience helped me learn that it's all in my head, and further convinced me to not think about it!!