You know that one guy/girl that's doing that thing you really want to do with your life, the one that's not only doing it but is very successful at it? In thinking about this is there a little part of you saying, "who do they think they are?" Well, there's a reason for that.
You don't envy people unless they have a thing you want. Dig for the reason you think you cannot have it and blow the damn thing up when you find it.
If you take nothing else from this idea maybe you'll learn what you really want from life. Realize what your jealousy is here to teach you and then try to wish the people you are jealous of the best going forward. They gave you a gift that you just realized you needed to open.
If you are on the receiving end of jealousy remember this thing and give others a break. If someone makes you feel like what you do isn't good enough remember this and give yourself a break.