I hate being jealous. How do I stop?

I really really hate myself for getting jealous so easily yet I can't stop it. I try to stay positive but it always comes back to me and I feel frustrated. I really want to stop being jealous and more carefree. I'm jealous of my friend, we are compared a lot by people at school because our looks are similar and so are our backgrounds. I would always think she's is much more funny, pretty and smart. I always try to stop myself and telling myself to be happy for her whenever she gets good marks or scores on tests but it's overtaking me and she's a good friend and I don't want to think of her like that. I just don't want to care about little things like. Please help or share any personal experience and advice.