Happiness vs Fulfillment
I think most people want to be happy, but I think its an inherently unstable state of being. Happiness is often experienced in contrast to a lack of it.
I feel that it is far more sustainable to aim for fulfillment. Fulfillment comes from setting a goal, working towards it and achieving it.
I think it also ties into the love for process vs the love for the outcome. If you are outcome-oriented, happiness ends up being tied in with achievement.
The love of process lets you find meaning in the doing of things rather than the result. Results are often contingent on many more factors outside out control or ability.