I think this life lesson ties in nicely with my previous one about being yourself.
In my opinion, envy is a pretty evil thing, with it being one of the seven deadly sins of our lives. Whilst I admit that I get jealous of peoples lives, I think it's a shame that we do. Being envious shows that you're discontent with your own life. It can tear relationships and friendships apart. It can hold you back from your own achievements, because you're constantly comparing your life to someone else's, and feeling disappointed that yours is nothing like theirs.
There's not always harm in feeling jealous, sometimes being a little jealous can motivate you to be better than someone, or work harder at something, but I think envy can make you into a particularly competitive person, and not necessarily in a good way, and it can also make you over look the good in your own life. You can become so concerned with how someone else is living theirs, wishing it were your own or working your arse off trying to make yourself equal to (or better than) them, and end up missing the important moments in your own life. A person may be rich and famous, surrounded by wealth, but will being envious of them get you their life? No.
Inspiration is instead what you should take from someone. Whilst I believe it's important for you to inspire yourself, having people that inspire you is also a good way to keep you motivated. If a life of wealth is what you seek, don't envy someone who has it, push yourself to reach your goals. If you want to have a fit body and feel confident in yourself, don't be jealous of someone who already has that, allow them to inspire you and work hard enough to become your own inspiration.
According to Dante's Purgatory the punishment for the envious is to have your eyes sewn shut with wire...so don't let green be your colour of choice, instead take pleasure in what you have. You may not be the most beautiful, the wealthiest, the healthiest or the most successful person in the world but you're alive and in control of your own life. Happiness is more important than envy.