First, stressing about it and being negative won't help you. Remember, there's nothing physical that allows you to lucid or not; everyone can do it.

Have you read any materials on Lucid Dreaming? I'd recommend Robert Wagonner's Gateways to the Inner Self. It doesn't tell you how to lucid dream (save one technique in passing), but it explains why you want to. Reading that got me lucid dreaming during a dry spell.