A friend of mine was saying that we need to focus on the things we have and not the things we don't have. We can put life in perspective by seeing the lives of others. He closed by saying, "I might be flat broke, but at least I'm not getting foreclosed on, either."
Excellent point. People would be so much happier if they realized that they are probably so much more fortunate than so many other people, that if they never had more than they currently do, they could still be happy and ok.
However, I have come to realize that people do need to focus on the things that want (not merely things they don't have, though). Desire leads to effort and progress and betterment. Being content is a marvelous and peaceful ability to attain, but if you really want more, have the courage and determination to go and get more. Just because you have it better than others doesn't mean you shouldn't want to have it better than you currently do.
Have you written something that you're actually proud of? Have you been published? Have you been published by somebody you respect? What do you actually want out of your writing? Go out and get it.
I used to think that it was a matter of "no matter what you do, you can always do better." That is a crippling thought, because it makes me a perpetual failure. But if you change the concept a little, so it says, "If you want more than you have, actually do every possible thing you can to get it," you can find yourself with motivation and encouragement the whole way through.