Goofy-Ass Obsessions

I ordered a new workout DVD a few days ago, and I just tried it for the first time this morning. I don't know what my problem is, but every time I start a new workout, I get paranoid that it's not going to work as well as the last one. This one is eighty-four minutes long, which is almost exactly what I've been doing. It's also extremely difficult, to the point that it's going to be a while before I'm even able to do all of the moves. Still I feel all anxious about not doing my old workout. I really feel like it has gotten me as far as it can, but still it worked pretty well for me for two years. I know that, if I don't get the results I want form this one, I can always go back to my old one, but it sill freaks me out. I swear, I stress about the strangest things.