More around positive reinforcement:
I often find that I’ve started a task but don’t want to finish it and would rather do something else. Being “self employed” as I am now, the really tough part is actually getting things done without a “boss” hovering over my shoulder (metaphorically speaking, of course). So when I’m half way through with a task, I just think of what I want to do when I’m done and don’t allow myself that treat/thing until I’m done. It’s really no different than those who get rewards in BF Skinner’s videos.