most of the serving sizes for cereal is 3/4 cup! I think most people fill the bowl up to the top. (I use to do that) It was tough to switch like that, but that's what fruit is for. You get use to it.
If you put a bowl of fruit and a bowl of candy in front of my son, he would chose the fruit. Of course he would spend the rest of the night telling me he wanted the candy, but he would eat the fruit first!!