I'm afraid of roller coasters!? Help?

I'm a 13 y/o girl and some of my family (like 12 of us) are going to Holiday World sometime this summer. And they all ride roller coasters (except the 5y/o and 10y/o and my mom) but I really really wanna ride roller coasters now. I'm not afraid of heights, it's just the drop and I have motion sickness but I really want to ride them! Any tips?? Thank you!