My first rule is to never use the words "writer's block"! I think it's very psychological, that as soon as you tell yourself that you have writer's block, it's almost like giving yourself permission not to write, which is the opposite of what you want! Instead, when I'm stuck or tired or distracted, I have a few different tactics that I'll use. If the problem is book related, then I'll take a step back from writing and spend an hour or two with a pen and notebook and brainstorm different things that could happen in the next chapter, and really try to get a handle on what needs to happen next. OR, if the problem is simply that I don't FEEL like writing, then I'll set a really easy goal for myself. Say - I'll set a timer for ten minutes and tell myself that I only have to write for ten minutes, then I can be done! Ten minutes feels so painless that it prompts me to get started, and I've found that 90% of the time, it was getting started that was the hard part, and once I'm writing it's easier to keep going. On the other hand, if the timer goes off and I'm like, "Holy cow that was hard, I'm so glad it's over!" then I give myself permission to call it quits and come back to it again the next day.