My answer will go against almost everyone here - I say that you don't need concern yourself with the amount of veg/fruit you eat on a daily basis.
Why do I say this? Many don't like them, and look at kids, they won't eat them.
Vegetables are touted for these reasons: antioxidants and nutrients. Evolution might also have something to say.
Antioxidants: The liver and kidneys process and expel exogenous antioxidants rapidly. The majority of oxidative activity occurs in the cellular mitochondria, where the body already has its own antioxidant system set up (glutathione is the main one). Any ingested antioxidant will never enter the cellular membrane. All that vegetable crap is taken in a run out quickly. Your body uses oxidation and reduction for many purposes, and does not want outside food interfering.
Nutrients: Vegetables have a lot, but most go in your mouth and out the shitter. You can't digest cellulose, so most nutrients are trapped in the cell and pass right through you. Chew all you want but you can't break down all those cell walls. There is also the issue of antinutrients, like oxoalate, which binds minerals and make them unavailable. I'm not sure how much of a problem that is though.
Evolution: Did people really care about eating vegetables? I doubt it. They taste bad and offer minimal caloric/nutritional value.
I eat them mostly as condiments and enhancers. Enjoy them at your leisure. I used to spend a lot of money buying them and finally realized that I was throwing it away.