How do I conquer my fear of snowboarding/ skiing?

I have tried snowboarding breifly, on the bunny hill.. I was petrified, I thought I would have a heart attack going down the hill so fast. It also took forever to convince myself to go down in the first place. Now, I know it stands to reason that I shouldn't take up a sport I am terrified of, but it might be beneficial to my job if I could at least swing it (ski retreats and so forth) and at the very least I know it's good exercise.