I know this sounds hard, but it actually works (I’ve tried it myself). It will take time!
Jealousy means that you want something someone else has, or you envy somebody else’s life.
If you keep repeating to yourself your emunah peshuta – that everything you have in life comes from Hashem, and this is the package He wants you to have. If you don’t have something, you are obviously not supposed to have it. Concentrate when you think of ???? ?? ?? ????. Your life is exactly the way it is supposed to be. (Maybe your test in life is to withstand without this {depending on how trivial it is})
Secondly, you should know that however perfect somebody may look on the outside, EVERYBODY, at some stage in life, has a certain amount of problems. Some more than others. Knowing that everybody has their own “pekel” will make it easier for you to be yourself and not envy somebody else.