I think this directly correlates with project management. To me, part of the secret to happiness is being able to connect how you approach life with what you do for a living. Then your passion will come out naturally.
Let me explain: I tend to classify people in three groups. Each group finds joy in what they do in life and that is related to their approach to project management.
Searchers are always looking for the next thing. If they don't like what they are doing, they simply change their direction. They like freedom and avoid tight schedules. They approach life from a "big picture" perspective.
Searchers are better at the beginning of a project. They are passionate about thinking how to approach the project to achieve the best results. That's what makes them happy.
Wrestlers have clear, defined objectives. They don't give up until they achieve their goals. From a project perspective, they are very passionate about doing the job until they get results. That is what makes them feel fulfilled.
Balanced people are equal parts searcher and wrestler. Life has taught them that both traits are needed to get results. I tend to think that seasoned project managers are balanced.
They find satisfaction in the ability to propose the big picture -- like a searcher -- and then pursue it until they get there -- like a wrestler. They are happy because they know they are contributing to build a better world.
If you are lucky enough to find and establish the connection between what you enjoy most in life and how you approach a project, you will enjoy every second of your profession.
Perhaps it will happen to you as it happens to me: You won't care whether you get paid for your work on a project because you've enjoyed the process so much.
The only thing that you'll seek is personal and professional satisfaction with your daily duties. It makes you happy and will bring out the spark you need to stand out of the crowd.
If you don't feel happy with your current job in project management, perhaps you should try to answer these three questions:
What are you looking for in a career?
What kind of person are you?
What are you willing to do, even if you are not going to be paid?