I have a little guy that is a picky eater!
I have the hardest time getting him to eat any sort of vegetables.
One night I explained to him "why" he should eat his vegetables. On this night it was salad and sliced carrots.
The carrots were sliced so that they were circles. I showed him how they looked like eyes and that they were good for his eyes. If he wanted to keep his eyes healthy and able to see he should eat his carrots. Which he did.
Then we went to his salad and I told him that it was good for his brain and heart. I explained what those two things do and what would happen if he didn't have them any more. He ate that up too.
Now I just have to remember to be slow and patient and explain "why" things are good for him and it's no sweat! :)