Sometimes after a break of a few days or weeks I find it hard to start work on a new painting (art) project. I have found it effective to use contrary thinking, so I tell myself to do no more than one hour of work and then I MUST stop, and I do this, then again the next day, say, an hour and a half, and then I MUST stop, which I do. By about the third day I am engrossed in the project, and stopping work is hard to do, and by then I'm over the initial problem. Works nearly every time and I have been using this technique for some years.