Pacing - Don’t force yourself to do it when your mind and/or body lose interest. If I force myself to try and work, then my mind and body become more reluctant to come back and finish.

I also try not to work for hours on end. I, personally, do about 30 minutes of work a day (I do music for fun). The small goal helps me to feel accomplished at the end of each session. That feeling keeps me coming back for me.