Science Fair?

One of my teachers is making my class do a science fair. I haven't done a science fair since the 8th grade. In one way I'm a little excited because I don't really get a chance to do that many projects that involve a poster. I think the most projects and presentations I did were in elementary school. All of the practice made it fun to do the next project and presentation, but now its just a chore. I keep putting it off and being unmotivated and now when I have to do a presentation I freeze up and get nervous. I'm not sure why that is?