A bit of good advice from p. 259 of Rolf Dobelli’s delightful book The Art of Thinking Clearly:
Like all emotions, envy has its origins in our evolutionary past. If the hominid from the cave next door took a bigger share of the mammoth, it meant less for the loser. Envy motivated us to do something about it. Laissez-faire hunter-gatherers disappeared from the gene pool; in extreme cases, they died of starvation, while others feasted. We are the offspring of the envious. But, in today’s world, envy is no longer vital. If my neighbor buys himself a Porsche, it doesn’t mean that he has taken anything from me.
When I find myself suffering pangs of envy, my wife reminds me: “It’s okay to be envious–but only of the person you aspire to become.”