What happens if you eat all the chocolate from the party at once? You'd feel sick, right? Sweets are yummy, but only a little bit at a time. The Bible says that "praise" (when someone says "Wow, you're so good!") is a lot like that candy.
If you clean your room just so mom will say "how lovely," and you get sad when she forgets to say it, that's a heart with a "tummy ache." The wise child cleans up and helps because he knows it's the right thing to do! He doesn't need to keep asking, "Look at me, daddy! Look what I did!" He does a good job even when nobody's watching.