How Do I Stop Eating Too Much?

How much is too much?

I don't know that I am full until my stomach begins to hurt.

I find it usually takes 20 minutes for my stomach to tell my brain that I’m full.
...So I let 20 minutes go by after my first bite, and before I finish my meal.
I chew really, really slowly and I enjoy each bite thoroughly.
Make sure to do nothing else while eating, pay attention to your feelings, be appreciative of every morsel you eat.