For stories, I have a similar approach. I jump at inspiration when I have it, or use prompts and themes to write around. The prompted stories are usually quite short, so relatively easy to complete for me, even if it takes several days. When there´s a theme to go by, it´s also quite sure to be finished... eventually. But fully original stories, especially long ones, tend to be stuck in writing for indefinite time. I never finished one of those, though I have several that are in production (I´m counting comics here too). Writing-inspiration usually hits me in the form of worldbuilding and characters. But unlike with drawing, you can´t just wing it from that point onwards. (as in, if you didn´t think of the colors to use in a drawing, you could technically blindly grab a few and make the best of it. But there´s no such auto-fill-helping-device for writing.) It needs a plot. And thought out details. And together with my less-than-helpful mindset of wanting to be surprised by my own ending and therefor not knowing where the story is going makes completing anything... difficult. I´m working on getting through that... I´m aware though that long stories will take a long time, so once again, it´s fine as long as I continue. And practicing getting things done with shorter stories is helping. I´m also working on a comic for myself where the point is to not plan far ahead, but think the story through in small segments so I can reach small goals in between that are both a safe starting-point if I continue or a possible ending-point if I don´t. Small, finished steps make it a lot easier for me to move forward than writing into a void. I think if I could apply that technique to a story where I can think of a climax to write towards, it would definitly help me to complete it.