לרפואת ר' יהושע מאיר בן רחל שרה בתוך שח"י
We all know the tenth commandment of לא תחמוד [or in the dibros shniyos - לא תתאוה] - don't covet your friends wife, car, house etc.
Many commentaries are bothered by how this is possible. We all want what [we think - often erroneously] will make us happy and one is bound to look at his friend's wife who seems SO GOOD while his own wife pales in comparison and desire her. Or one lives in a dilapidated two room apartment in a dinky neighborhood and then drives through Woodsburgh and sees the mansions there. How is he not going to covet a house for himself? The list goes on and on.
The avodah is כפיית הרצון - overcoming one's natural will and aligning it with the will of Hashem. One must learn to say, think and feel that if this is what Hashem wants for me then this is what I want for myself because NOTHING COULD BE BETTER. So it is an avodah of Emunah. It is no coincidence that the sefarim say that the tenth commandment corresponds to the first, אנכי ה' א-להיך - belief in Hashem. If one truly believes then he is at peace with his lot and truly happy.
One of the most brilliant Jewish maxims in history: איזהו עשיר- השמח בחלקו. Wealth is not revealed by looking at one's bank statement but by looking into his psyche.