Why haven't I had a lucid dream- what have I been doing wrong?

So the other week I watched a video on how to lucid dream. I've been keeping a dream journal for roughly a month, and some nights I forget to write my dreams down. Also, I'm not always the most descriptive in my entries. The man in the video said that it takes some people longer than others to try to lucid dream.... what are your experiences? What am I doing wrong- is it the inconsistency? Please help- and thanks for your answers!!