How to cure my roller coaster fears?

I'm actually having the same problem, I've had it for years! I try to push myself on the roller coasters but I just cannot do it. I am going to an amusement park very soon with big roller coasters. I am going to try a roller coaster, hopefully (if I don't back out again). I want to go on them, but I just can't get past the fear of how my stomach will be, if I will like loops, and so much more. Hopefully we can cure this roller coaster fear!.
=============================
Commercial Glass washers|Ice Machines