I am a recovering Sugar addict. Recently I made the connection between continuing to eat Sugar and carbs and feeling like I'm 200 years old. Then I realized it was a Candida overgrowth problem, all my symptoms fit the profile. I hadn't done Atkins-dieting in a while, but recalled that whenever I di it, I felt 1000x better physically and clear-headed.
So first off, the revulsion at the thought of this yeast/fungus invading me from inside my body helped me to quit eating Sugar and carbs.
Next, when confronted with a plate of cookies at work, I looked right at them and said "That is food for fungus and yeast!" Makes'em look a little different, a little less desirable...
And here's a tip: it is not "going off" sugar that gives you the brain fog, it is the sugar itself. So go off it and get your head clear. You'll see.