The definition of "covet" is to yearn to possess or have (something). It is not a sin to covet. It is a sin to covet something that belongs to someone else. If we did not covet at all, we would have no need to petition God for anything.
You can't want a woman or a man in your life that is already committed to someone else.
You can't want a job that is assigned to someone else.
You can't want someone else's car, home, or anything else.
If you don't have much money, and you meet a rich man, you should not covet his money.
God wants us to appreciate and be content with what God gives us. The more we prove ourselves as good stewards in little, God gives us more. (Luke 16:10) If we can not learn to appreciate what we already have, how can we be trusted to have more?