This happened to me for a time because whenever I did reality checks, I wouldn't really do them. They started becoming mundane and robotic . You have to really get into those reality checks and really ask yourself with a genuine interest, "Am I dreaming?". If you have that genuine interest to do so it will stop distractions and you will overcome this obstacle.

Also, a strong desire to Lucid Dream like, "I'm going to Lucid Dream no matter what!" will stop distractions and also make you more aware when doing reality checks in general.