How to NOT Rationalize?

Options
It's after 5:00 p.m. and here is where I start to bargain with myself. "Spend the last 400 calories on a frozen yogurt!" or, because you ate healthfully and consciously all day, you can eat a sugary item now.

I can't imagine these tricky thoughts are new to anyone attempting to eat reasonably.

Is anyone interested in pointing out to me exactly WHY I shouldn't eat the sweet thing, EVEN IF it's within my caloric range for the day? If I can get some slaps in the face up in here, I'd sure be grateful.