Ambition and Happiness

One more post on The Happiness Project. Going back to the idea of the relationship between happiness and work, how does ambition fit in? The author doesn't have any conclusion on the relationship between ambition and happiness, and discusses it briefly:

There's a common belief that happiness and ambition are incompatible. Many ambitious people I've known seem eager to claim that they aren't happy, almost as a way to emphasize their zeal, in echo of Andrew Carnegie's observation "Show me a contented man, and I'll show you a failure."

Studies show that many creative, influential people in the arts and public life score above average in "neuroticism" (i.e., they have a greater propensity to experience negative emotions); this discontent arguably urges them to higher achievement. Other studies, however, show that people tend to think more flexibly and with more complexity when they're feeling happy.

Quite frankly, I'm not sure how I feel about this. A number of my friends and peers are people that I would characterize as 'ambitious' (even if they wouldn't necessarily describe themselves that way). But does that mean that they'll always be unhappy, striving for something more?

Perhaps the key is to find happiness in the struggle for higher achievement?