Good For Me and You, by Mercer Mayer, Harper Collins, 2004.
When my son was a little over a year old, my mother bought him this book for Christmas. This book is about making the right exercise and dietary choices. I thought the book might have been a bit advanced for my son at the time, but shortly after he received the book, my son climbed up his bookcase and took a bite out of the back cover of the book. Um, I guess he understood the context after all.
Now my son is five, and he adores Little Critter. We even have a toy Little Critter in our house, who apparently misbehaves at exactly the same time my son does. As a five-year-old, my son understands that playing outside in the backyard is even a better choice than climbing the bookcase, and that an apple for a snack is a much better choice than a paperback cover.
All in all, this Little Critter book is yet another winner.