Unconcious. I pick up aspects of other styles like a sponge, so it changes a bit over time.
There's what I want to call techique (you might emulate MLP when you're drawing, or a specific anime, etc.) and then there's the individual variation in the way you draw each stroke and stuff. The second part is what is more important to style in my view, as it's fairly constant (although it does shift a little over time) You can't really train it though, as it's generally only the most subtle hints that make it possible to seperate the works one one artist from another.
I've been trying to "find" my style too. I've heard that the way you find it is by drawing, drawing, drawing (or painting, sketching, etc...whatever is your medium). Just do it again and again and again and it will happen. Of course we are influenced by others, as well as things we might not realize influences us (like where we live, our friends and family, events, etc), trying to imitate or in some cases trying not to imitate others, and so forth. Consciously and subconsciously we try new things, discard some and hold onto others.
Another thing I heard about style not too long ago is that our style is made up of our "flaws." Which I thought was really interesting. It is the flaws that make our works unique from others. So according to what I read we find our style by deciding to keep, emphasize or eliminate these flaws. [link]
Unconscious. I never really watched anime or manga when I was little, and I never tried to copy or draw one of my favorite characters so I naturally did my own style, which has grown and changed over the years, but still is completely my own.
I found my own style by looking at other artists and trying them out for myself, then combining them. I also just do random experimentation doodles sometimes, just messing around with brush settings, colours etc. You won't find your style by looking for it, you will find it by accident while practicing
I don't believe style can be formulated, the closest it can come is probably out of necessity. I know some people develop their style because they work in editorial which is something where you need a drawing made in 4 hours and e-mailed off to some newspaper when the story breaks.
A bit of both, actually. My most natural style is influenced by comic books and anime which I've absorbed throughout my whole life. Then there's the conscious effort of trying to make things look somewhat accurate (anatomically speaking). Then when I had somewhat of a grasp on anatomy, my drawings became a stylized mix of both. I'm still trying to figure out what style I really like (so I guess that's a conscious effort), but no matter what I do, all of my art is starting to have a consistent look to it.