Sure, I'll Do It

I really need to learn how to say no. It's a skill I haven't quite mastered. I have an incredible fear of public speaking. So what do I do when a lady from my church calls and asks if I want to be in a skit, this Friday? I say, sure. WHat in the world was I thinking? Was I even thinking at all? Couldn't have been. I'm so freaked out. And to make it worse I have the worst memory. So how the heck am I going to memorize the lines? And is this skit just for my church? Noooooooo. Of course not. It's for women's world day of prayer. It's being held at our church this year so there will be ladies from lots of other churches. No pressure. Just representing our church in front of our whole community.Ugh. I know it's good for me to do things outside of my comfort zone, but it FREAKS ME OUT! Here's hoping it turns out great.
What freaks you out? And how do you cope? I could definitely use some pointers here.
~Ms.Random