I agree that the media are trying to sell us the idea that happiness is a state to be obtained by achieving whatever is the latest definition of "success" and I agree that this is bad. But if we're trying to avoid that, let's be careful not to run into the other extreme: confusing happiness with contentment.
It is normal and natural for human beings to want more and strive for it. I think that the idea of "having enough" goes against our nature. Sure, I probably have more than I absolutely need for survival. Sure, I guess I "have enough" according to some arbitrary definition of "having enough". I most definitely "have enough" when you look at it from the point of view of someone who has less.
The point I took away from the article is that we should enjoy what good we have. That's a message I can agree with: even if you want more, don't forget to enjoy what you have now. But I can't take that one more step and settle down and say "That's enough." I still don't see why I should do that. Perhaps it'll come to me some day, but for now, all I can think of when people offer me that idea is this passage from Frank Herbert's "Children of Dune":
"[...] Tell me, Namri, are you content?"
"No." The words came out flat, spontaneous rejection.
"Then do you blaspheme?"
"Of course not!"
"But you aren't contented. You see, Gourney? Namri proves it to us. Every question, every problem doesn't have a single correct answer. [...]"