I am at my happiest when I'm problem solving and a large part of writing is for me a lovely labor in problem solving. Every act of discovery in writing involves a process of figuring out why I'm not seeing what I need to see. Niggling feelings, discomforts, a sense that you've forgotten or overlooked something, a sudden curiosity about what if here? - these are priceless. They are the bases of problems and lead the way.