An interesting problem, self control is the singular key to losing weight.
There is no other way.
You will have to say NO to many foods, to others but mainly to yourself.
It is intake of food that governs your weight, so the more controlled is your intake, the more your weight will be in your control.
There are many factors to losing diet, as is discussed further on this website.
Each and everything discussed further is dependent on your level of self control.
If the pizza image has made you want to eat pizza, and you control yourself, that is the first step.