How do you find themes in a story?

EX. Don't watch too much TV or you will become dumb.

http://www.learner.org/interactives/literature/read/theme1.html

This is one of the best explanations of "theme" I've ever found. It's perfect!

PS -- A friend told me long ago that she could always figure out the theme by asking herself, "What's the author's hidden message?" Excellent method.