That's excellent advice. Center yourself in reality, instead of turning off your mind.
One thing that's helpful to me is thinking of it NOT as an ON/OFF switch (I've blown it, might as well eat a whole cake and start off fresh tomorrow!)
It actually works as a bank account. When you spend a little more than you meant to at the mall, do you say, "Heck, I might as well max out the cards and overdraw the checking account too."
Of course not. Because you know you always will have to pay it back.
Your body is the same way. Stuffing it with excess carbs & calories is just pushing your goal further away. Don't let a slip turn into a binge and turn into a blown week.