I used to be obsessive about writing stories in order. I would start at Chapter One, Line One and plod my way through to the end, and if I got mired down, I would just tread water and force myself to put words on paper until I somehow got through it. Those times, which happened fairly often, were no fun at all. In fact, they really sucked the joy out of writing. I'm sure what came out was not my finest effort, either. But I had written two books that way and I knew it worked in the sense that it would get me to the end, even if it was sometimes utter misery.
I should note that I'm a plotter, so I know what's going to happen—in detail. I was just afraid to jump ahead because I worried that the story wouldn't flow right. But then I finally got tired of writing scenes just because they were next on my list, and starting writing whatever scene I was in the mood to write. The scene that was burning a hole in my brain and seemed like it would be SO much fun to jump straight into with both feet.
I only took the plunge about a month ago with my latest WIP, so it's an experiment in progress. I know that my first draft is going to be a lot messier than I'm used to. It will have more bits that need to be stitched together, and will need more polishing. But you know what? I'm having a great time. I'm looking forward to my writing time again, instead of procrastinating by any means necessary. And that's the ultimate point, right?
You probably have your own habits and rituals and systems to get you from point A (awesome idea) to point B (finished novel). Or maybe you're still learning—I certainly am. Habits and rituals and systems are totally necessary for what we do. But when they're broken or just not working the way they used to, don't be afraid to toss them out the window and try something different.