Everything starts in the mind. That's why Jesus taught the importance of our thoughts, because all transgressions (murder, theft, adultery, etc) start as thoughts. Thoughts are powerful... and can change one's life, for the better or for the worse. So Jesus' teaching on changing our thinking is pure wisdom.
But getting back to your disagreement with miseryindex's comment about God's commandments....I agree with what he said. But to put it in a less big-picture way, I'd say God's commandments are for our well-being and safety.
I'm sure you would agree that a good parent has some basic rules for their children, right? Don't run into the street without looking first, don't touch a hot stove, don't hurt your little brother, bed time is at 8, etc, etc... Obviously those rules for their children are for their own good, and their safety. Why, because their parents love them.
In the same way, God's commandments are for our good because God loves us. I know that you don't believe.... but for the sake of argument, assume God exists and please answer this question in a theoretical way. Who would know better about the best way to live: The One who created us and who knows us better than we know ourselves..... or a regular joe schmo with limited knowledge? Again, you don't have to be a believer to answer that in a theoretical way.