Your energy or impulse will be sapped. Barker found that writing was a much more effective way to combat depression. Break off in the middle of a sentence. If you are at a difficult place, move on and start work in an easier place before you break off. Leave your space clear and have your favorite music, your tea or whatever, and your tools ready for when you come back.
Barker also suggests setting a time limit for working.
If it's open-ended it's harder to begin. I write 2,600 words a day, no matter what, good or bad. I can survive the feeling that my work today is inferior, because I know I will write again tomorrow. Every day that you make something, that's what you made. It's probably not as good as you think it is at the time.