How do you make energetic kids stay put while they're in Church?

I tell my 3-year old boy that we're going to the house of Jesus every Sunday. He has a concept of who Jesus is and he knows that Jesus wants him to be a good boy. He knows that J has plenty of wounds and blood because he was beaten by the bad men, so I always remind him that if he becomes naughty, the bad men will hit Jesus again and He'll have plenty of wounds again. I don't know if I'm doing the right thing, but it's effective every time we're inside the church,