How do you keep from being cynical, angry and bitter about the hand you've been dealt?

How do you keep from being cynical, angry and bitter about the hand you've been dealt? I find myself getting jealous of my colleagues, friends and cousins. I know i should not compare myself but sometimes I can't help but feel "i could have been that person" when i look at them, where they are in life and then get really depressed and angry about it all.