You must think about habits when developing them, but once the habit is practiced for a long time, it actually forces the brain to work and think about the physical actions that have become your habits. Even if you may not be conscious of what you are forgetting, the repeated physical actions have caused the brain to feel that something is wrong and make you try to remember. When you fail to perform a habit that is deeply ingrained it can affect your mood and attitude in a negative way, and maybe it will spark the brain into remembering what you failed to do.