That's a very hard question.
What the hell is consistency?
Well, for starters, consistency definitely lives in many realms.
A writer needs consistent habits. Hell, I do know writers who live insane lifestyles, but that's because they are habits of their own. I definitely believe that the average person overestimates their abnormalities, but some people do have very different sleeping/eating patterns compared to the norm. However, regularizing this aspect of your life is definitely the first thing to do.