Many people wonder if there's any use for keeping a DJ. If u ask someone, the answer is usually 'There's no point in having an LD when you can't remember it. This boosts your recall enormously.' Well, that's true. But that's not the only reason. I believe recalling dreams on itself helps you get lucid. This is why:

By keeping a DJ, your recall will improve. You focus your intention on remembering dreams. After a while, your brain knows that it's important to remember dreams. To remember it, your brain will pay more attention to your dreams, which is required for a good recall. Because your brain pays more attention to your dreams, you'll recognize something as weird much easier. Thatwill activate your logic centre.
So: DJ--> better recall --> brain pays more attention to dreams --> easier recognition of dream signs --> more lucids

Please note: as far as I know, this has not been scientifically proven. It's just a theory which makes perfect sense in my opinion. It's meant to explain how usefull keeping a DJ can be