Being and staying productive is often a hard thing to do. It's hard because most people don't know how to be efficient with the time they have. I've struggled with this most of my life. I've read dozens of books on time management, productivity and goal setting.
Single and best way I have found to be the most productive is to do less. It is to eliminate.
Eliminate unproductive activities and focus on only a few.
What you want to do is develop a habit that will dramatically improve and change your work, yourself and your life.
First it is to find what it is that you love doing. What are your passions?
For me it was the decision on focusing on environments and level design. When I first got into 2d and 3d I wanted to learn everything. Perhaps you know what I am talking about. I bought books on Bryce, Poser, 3ds max, lightwave. That's just to name a few. I wanted to be good at all these programs. Not to mention I wanted to texture and animate and paint in oils as well as program in c++.
At one point I thought I could do a mod all by myself. I was nuts and I had no focus.
Narrowing down your focus on what you love doing and completely eliminating the rest will help you being most productive.
Focus on only one key goal, one key passion at a time.
Here is the single solution:
Starting today. Dedicate yourself for 30 days to work on your map. New map, old map it doesn't matter, but for 30 days and for minimum 30 minutes per day work on your map design environment; or it could be any other activity that you choose to do.
Everyday for 30 days and only 30 minutes.
What you will find in those 30 days is that you will develop a habit. This habit will dramatically change your work, your life and your art.