Writing is definitely a discipline. It's freakin' hard work.
Well, good writing is, anyway.
Anyone that tries to tell you otherwise is either lying or stupid or just not very good at it. Even those that have "made it" will tell you, in my experience, that writing is pretty much a cruel mistress.
Whether you write for yourself or for an audience, whether you want to get paid to do it or you want it to just be a hobby, you have to work at it every day. This is something I struggle with constantly - I spend so much of my day writing things for other people, using their topics and ideas, to their specs, that by the end of the day, I don't have much in the way of energy left over for my
own topics and ideas.
I've never really wanted to do anything other than write, and when I was younger, I thought writing for a living would be something resembling the easy life. HAH. The idiocy of youth. I had no idea how much I'd have to bust my ass to get exactly nowhere that's discernable to anyone but myself.
I know that what I am doing now is putting the first floor on the foundation of my writing career (dug the cellar with my old job, laid the foundation when I took the leap to freelance about 2 years ago), so I am okay with that, but it's still damn hard a lot of the time and I often wonder if I shouldn't just quit and go flip burgers.
But I don't. I just keep on keepin' on, because I know that's just what you have to do.