I think we all have moments like that. I just try to remind myself that someone else's happiness has nothing to do with mine. I also try to remember that everyone has problems, too. Like when you scroll through facebook and you see all the happy photos of families, parties, friends, vacations, etc. Just remember that people are more likely to share the good in their lives than the bad. And try to be happy for them because their successes have probably been preceded by times of bad fortune, too.