How can i stop being scared of roller coasters?

i was always scared of roller coasters, oneday in the 5th grade i went on a field trip to busch gardens and my friends made me get on a rollercoaster called kumba. it was really scary but kind of fun. i was 11 years old. now im 15 and im going to busch gardens tomorow with my friends. i wanna be able to go on rollercoasters and have fun but in the end i get 2 scared. i hate the erfly feeling u get on a drop, is there anyway to get rid of it?