Intensive periods of creative work will also require intensive periods of regeneration to balance out. It's not so much as suffering from writer's block as it is a process of breathing out and breathing in. With practice and discipline you can "force" yourself for longer, but if you are unhappy creating at that moment no power will get you to sit down and pick up that pencil without feeling unhappy. Then it helps to just go out and "live life" a bit until you've collected some more inspiration ;)