Pre-presentation Jitters

It's 1.5 days away to my Brown Bag presentation. It's not the first time I presented at a Brown Bag, and definitely not the first time I presented my works. But why the heck am I feeling so jittery and panicky? Maybe the last few times I presented, there were nicer people around, and I knew what I was talking about, and I was interested in what I was presenting - gay men and lesbian discrimination - an issue I feel strongly about. But now...I'm presenting something that is someone else's, something that doesn't belong to me, something that someone wanted to investigate. Definitely, I had a part in the research topic but the results I'm presenting are different from the question that I was interested in. I need to calm down. God Help Me!