In my opinion, happiness is not a state of affairs but a state of mind. This is the reason why some people seem happy and content with what little they have, while others seem to bicker at the slightest problems in their life. Yes, there are carefree people who go with the flow while others like to have some control over their life, but at the same time happiness comes from within. Achievement of a goal cannot 'define' happiness unless the person 'decides' that this is how he'll be happy. We ourselves put it down that we cannot be happy unless we are in a particular state of affairs, not our minds. Yes, it is hard to be cheery and gleeful when you're broke and there's a death in the family but it's not impossible to come out of it. And that is the only true way we can be happy or unhappy; we should not let the state of affairs be our guide but our own mind.
And you know something, for those goal-oriented, passionate people? It's better to be happy rather than ticked off with your fate half the while because it reduces the strain on your head. Stress is good but in measured doses and if you don't let in some fresh air every once in a while, you compromise your abilities to handle problems and actually slow down yourself in achieving your goal(s).
So coming from me: learn to be happy in the most adverse of situations because this is something you decide--be thankful of the blessings we have, because there are almost a few million people who cannot even perceive the material and emotional tranquility of our lives. And even if not, what's a life without some challenges? So face them head on with a grin on your face.