The advice to "follow your passion," or "follow what you are good at" is stupid advice. Why beause someone is assuming you know what you're passionate about or good at.
And most people have no clue; I didn't, and there are moments when I still question what I am passionate about or good at. Instead, I have found that you need to ask yourself a better question -- "What can I do that adds value?"
Let the problems of the world reframe your decision making. Then take an inventory of the skills you have and interrogate which ones you will solve those problems. And yes, you will need to acquire new skills to add value. But that is the easy part; there are endless educational options -- lynda.com, iTunes University, CreativeLive, etc.
When it comes to pursuing self-interests everyone is participating in the same race for the same trophies -- money, fame, power, and status. In part, because they are following their passion or what they are good at. But if you are trying to solve a problem then you are woking on leaving the world a little better than how you found it.
And that is something worth working towards.