Well, besides my blog, which I've been writing since 2009, and some other stuff, I've written a 220,000 word novel. It's not about dentistry specifically, but it is about the business principles I've learned over the years and from some awesome mentors and teachers. It contrasts what we might call commodity capitalism with bespoke (unique, customized, personal) capitalism.
First I'll say this--though you're just doing this for yourself now, Bumblebee, the real purpose of your art is to ship it out the door and make a difference with it. So keep that in mind and don't keep your light under a bushel for too long!
Now, it may be different if we're talking fiction or nontiction. I'll tell you what happened to me though, and how I stayed productive.
I was surprised--I'd almost say shocked--at what happened when I created characters and started writing a novel. After a little while, they became real to me--as much as any of the people I know. This will no doubt sound odd, but it's as if they were talking to me, telling me of the events of their lives, and after a point it never felt like I was making up the story. Accomplished authors tell me this is a rare and coveted thing. For that reason, it never seemed like work, and I almost never got blocked. The worst that would happen is that for a few days or a week or so nothing would really come to the surface, but I was confident that things were brewing and they always were. Once I sat down to write again the words would just fly out of my hands into the work.
Here's the part that's relevant to you. I'm sure that what was really happening is that I had learned a tremendous amount from the writing and live seminars of a few brilliant thinkers. And I had learned even more from practicing dentistry (and dealing with people) for a number of years. All these thoughts and ideas and feelings were probably simmering for a long time and at some point they just had to come out.
So that's where your discipline and productivity should come from. Not so much from saying "I'm going to write for an hour every day, two on Tuesdays." But rather from your passion for your subject, and for the goal of making a difference with it.
Don't worry if it's a technical subject within dentistry and not a story in the accepted sense of the word. Make it a story anyway. For instance, I love writing blog posts about how we create adhesion to enamel and dentin, or the nuances of how we assemble dental implant component stacks with threaded fasteners, or dozens of other topics in our field.
Caring deeply about your subject is the key to productivity in writing. And the more you write, the better you'll get at it. Keep at it!