"You shall not covet your fellow's house. You shall not covet your fellow's wife, his manservant, his maidservant, his ox, his donkey, nor anything that belongs to your fellow."
Now we are up to the hardest of all commandments. Do not kill... steal... lie - these are actions and it's understandable to obligate people not to do things which are immoral and destroy the society but not to covet... If i am really jealous of someone else's house or car but i don't commit any transgression - is it that bad? So bad that it's placed in the 10 commandments itself!
First and foremost it teaches us that we have an obligation to control not inly our deeds but our emotions and feelings as well. But how? As a therapist i know that certain thinking patterns create emotions. When you change your thoughts - you change your emotions. So what stands behing envy and jealousy? Most of all, the lack of appreciation of my own life, destiny and accomplishments. If only i would have his car - i would be like him... G-d doesn't want it! With this particular commandment He screams to everyone of us "You have so much potential inside of you! There is so much work to do achieving your own mission! Don't waste your time and energy trying to occupate someone else's place in the world. Realize how valuable your own life is! And believe that I gave you absolutely everything you need to achieve your mission in life."
That way of looking at life will not only relieve us from envy and stress but will help each and everyone of us to achieve peace of mind and clarity which is so much needed in our generation.