Something like that will come to you, naturally. You can't really force it upon yourself.
My images tend to have strong emotional component - be it landscape or portraiture. What's what I see in a lot of things and that's what I tend to photograph. When asked, I usually say my favorite area is portraiture but that's not exactly correct. I found this by looking back on my photographs in the past few years. It was also prompted by a photographer I respect and admire stating, "you seem to have a good eye for composition. You seem to be photographing what looks good, but I don't see a continuing theme."
I am not an activist photographer where I seek to find subjects to make statements. I tend to photograph subjects that interest me WITH emotional component. That's what I do... since I am not selling my work, that's enough for me.