It would seem that it's a popular misconception that we need to follow our passion to be happy, according to some recent research findings; it may even be harmful to do so.
The real problem, it seems, is one of expectation - we may set out with a fixed idea of what we want, where we're going, how to get there, and so on, simply because it's our passion. What that means is that if (when?!) we encounter any obstacles or difficulties, or things don't progress in the way we anticipated, we're much more likely to give it up as being hopeless and unachieveable.
Alternatively, if we take a more flexible approach from the outset, remain open to other possibilities, we are much more likely to cope with the challenges and perhaps see them as opportunities and alternatives instead.
I recently had an experience of this. Without going into specific details, I was faced with a decision about my future and because of my quite specific idea of what I was seeking, ruled out a possibility. However, as time progressed, I began to doubt and reconsider, until eventually I did a complete u-turn (and there's a whole other topic - it's not failure to change your mind!). It dawned on me that I was looking at matters from an unrealistic perspective, that it would be much more constructive to look at potential rather than limitations, and I'm so glad I did. Wonder where I would be now if I hadn't?