Getting some exercise before starting to work
Working in natural light. I've learned to get all my ideas down in the daytime while sitting in natural light (luckily I have a window at work)
Writing my outline and ideas down on paper by hand - adding diagrams, notes, etc. Later I use my handwritten notes to guide me and keep me on track as I type out the report, etc.
No coffee (tea's OK) and no junk food - it just makes my attention issues worse
Fresh fruit on hand - a variety is important to me
Water... lots of it
Rewards! I write 10 sentences and I get to... (insert whatever works for you)
Walking around and speaking my ideas out loud... quickly sitting down and writing them down or typing them (I don't do this one at work)
Headphones with music. It blocks out the world and I can tap my foot to the beat. If my foot is busy with the tune, I don't get as distracted. Maybe the part of my brain that gets distracted needs to be doing something (this one really works for me)
Writing whatever comes to me (no second guessing), then setting the work aside for an hour or so... then going back to it to edit
Printing my work and editing from print (an editor told me this trick - he never edits from electronic copies... always the print)
I follow some of these guidelines already, except for the staying healthy part -- paying attention to what I eat, exercise, etc... This is what I am working on now. Manny, thanks for the inspiration!