I'm a great believer in cross training. Though I am hardly an athlete, I do know that changing my workout from time to time is a good idea, and I get better results.
The past couple of days I have changed the time I work on my manuscript. Instead of waiting until I am done with work, I write now before work. Like a change in a workout, I'm finding the change creates good results.
Now, I'm going to go write some more (even though it's after work). Twice a day is even better!