I'm not sure whether envy is actually the besetting sin of our profession--pride is an obvious challenger, with gluttony, wrath, and lechery making strong showings come conference time--but it may be the one that most of us wrestle with the most often. I know I do.
Envy isn't always destructive, and I've gotten better at limiting my envy to specific, tangible things: I envy my friends at other institutions the amount of travel funding they receive, or the frequency of their research leaves. Granted, this may not be a productive way to spend my time (although I suppose, for people who are not me, it could lead to redoubled efforts to conserve or use more wisely one's own time and money), but it's an expression of frustration with my institution's more limited resources rather than resentment of my friends for what they have.
I hope I'm smart enough not to envy most people their jobs, much less their lives; all jobs have trade-offs, of course, and it's impossibile to assess the quality of anyone's life from the outside. Some of my friends at research schools have more grading than I do, because when they teach lecture classes they don't get TAs (or they get only one for a class of 80). Others may indeed teach only a few dozen students a semester, but are swamped with orals or dissertation committees. When it comes to teaching/research balance, and to the health, happiness, and sanity of one's department, I've got it extraordinarily good.
Nevertheless, I still experience occasional fits of anger, frustration, or bitchiness that only later reveal themselves to have been partly motivated by envy. I'll be ranting about someone doing something SO UNACCEPTABLE or being SO CONDESCENDING, and then stop myself, wondering why I care so much--and realize that my anger was rooted in some presumption about how great that person's personal or professional life must be (with the allied presumption that, if I were in the offending party's place, I'd be much nicer or more generous).
As I say, it's something that I wrestle with, and nowhere more peculiarly than on those occasions when I've felt myself on the receiving end of other people's envy. Each time it's dawned on or been suggested to me that envy might be the reason a professional friend is suddenly making snide remarks or gossiping about me behind my back, my first reaction is to exclaim, "but why would anyone envy me?"--and then produce a list of all the ways in which that person's professional life is even better than mine.
I should know that that's just the way envy works--that since it's all fantasy and projection, I'm as reasonable an object as anyone--but it's disconcerting to think that someone might waste as much energy on me as I do on others.