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I think if you feel that way, then the best thing you can do is to redirect that energy from a negative direction to a positive one. If you want what they have, then the question is how you can obtain it as well. I don't think there's anything wrong with your brain: reframing and rechanneling these emotions is a skill that you can practice.
Sometime the answer is just "time" and you can take comfort that it's something you can look forward to. Sometime the answer is "effort". For me, I felt envy when it came to relationships and appearance. I obtained the first by putting myself out there and going through the stress of dating, and for the second I put a lot of practice into makeup and learned a lot about fashion. There are still things that I feel a bit jealous of, like shilouette and voice training: these things are definitely addressable, just harder for me and I know that with effort (and time) they are achievable.