I once envied a friend of mine because he stopped smoking. It made me quit smoking with relative ease; until then I never imagined that I would ever be able to stop, that it would follow me until I died of old age. Now I've been smoke-free (or at least nicotine-free) for well over a year and I actually can't see how I was ever able to smoke cigarettes in the first place; every day for 5 years my body has been a train wreck and my mind has been clouded from tar and physical pain.
Also, whenever I envy someone's talent, I find out that I have talents in the same field. Perhaps not as great as in the person I envy, but acceptable. For instance, I recently fell completely in love with Noel Fielding's artwork. That inspired me to start painting and I've discovered, for the first time in my life, my own style of painting; of course it needs to be refined as I'm still quite new to the whole thing. But I still envy Noel's abilities and even his life story of how he became an artist; I don't have a life story of being exceptionally good at arts, I just started out wanting to become good and that torments me, as it's just not that original of me. Sometimes it torments me so much that I just feel like giving up, but then I come to my senses, smoke a mild joint and start painting something.