Some thoughts why I am not going pro anytime soon

More then a week ago, I reviewed on blog the “Going Pro” e-book from Digital Photography School. There is a lot of great tips in the e-book on how to connect with clients and promote your work. But there were really two tips important for me. Two things I need to do first before I can start taking advantage of other parts of the e-book.
These are, in this order- deciding what photography genre and business type you want to pursue and put together a portfolio.
And I have been working on putting together mine for a while. Probably at least a year of thinking went into that, and almost two months really searching through Lightroom library. But the problem is here. I am sure I can pick 10 great images out of everything I have in my Lightroom library. The biggest problem is that those images need to go together, tell a story, be connected by something. I have some great landscapes, few good food images, many plants, fruits, airplanes, cars… Just about everything.
And those days, you need to be good in something, specialize in something, to be successful. Maybe not even to be successful, but how otherwise you know who your market is? So it is best to pick one photography genre, and get exceptional in it.
And I just cannot decide what is my favorite subject. So far, I am just taking any occasion to take photographs. I go to air show, I photograph airplanes. I go to the National Park, I photograph landscape. Opportunistic photographer I am.
But this way, I cannot put together a concise portfolio. Well, OK, I probably could, but I will still need to focus on one subject.
Until I figure out what it is that I want to photograph most, I cannot take any serious step further. And I am thinking about it hard for a long time already, and still not getting any closer to conclusions….
How about any of you, reading this blog? Are you a universal photographer or do you specialize? How did you find out, what is your favorite subject? Any advice?