How do I control my controlling issue?

I have a fear of tubing, like whenever I go I freak out and cry NO JOKE, on Monday I am suppose to be learning how to wake board with a couple of my guy friends and my BFF, she has wake boarded before but not in a long time so she will need refreshed. When ever I am being towed on something or sitting behind someone who is driving I freak out cuz I cant control anything, and I hate going fast, so when someone is like driving on a 4-wheeler, jet ski, snowmobile, something small and easy to fall off of, even chairlifts but I am over that now cuz I love to snowboard, but any of those things I freak out and start crying, I would really like some advice before I go on Monday thanks