Why do we go the opposite direction from what God says is for our good?
Because fallen human nature is rebellious and Satan, God's adversary, urges the opposite. When God says something is best not to do, Satan says do it; when God says it is best to do, Satan says don't. So people turn from God's commands, which are for their good, and bring heartache.
Les teaches that this goes back to the Garden of Eden, when Satan approached Adam and Eve and got Adam to eat, bringing sin on the scene, and Satan became God's greatest adversary. He illustrates it with a child: tell a little kid he cannot go through a door, and as soon as you turn your back, he will try to look behind it. We are no different. Just as soon as God says, thou shalt not steal, thou shalt not commit adultery, human nature says, I'm going to try it. Everything God says is best for us not to do, Satan says do it; everything God says is best for us to do, Satan says don't do it, arguing the world isn't doing that, so why should you? Les explains that everything God told the human race for our own good, from the human side we always find ourselves going the opposite direction. The resulting heartache comes because people have gone contrary to what God set down as our best. God knows what is best, and no society can survive by totally going contrary to these Ten Commandments, because they are basic.