About a year ago I realized that the only way to survive a sedentary job like writing was to make exercise a part of the work day.
I now begin each day with a strenuous 90 minute session of Bikram yoga.
The results have been pretty good: lost 50 pounds, sleep better, get more work done, anxiety and worry largely a thing of the past, more cheerful.
I'm better able to withstand mental and physical stress of writing. (After a day of writing I'm exhausted and dripping with sweat.)
Wish I'd fully understood the necessity for daily vigorous exercise as a prophylactic for sedentary work 30 or 40 years ago. Maybe I could have avoided some of the health issues I've had to wrestle with over the past few years.