Ask HN: Any productivity method veterans out there?

In the past, I've tried many different productivity methods (most prominently GTD), and the longest period I've managed to stick to one was maybe half a year. I feel like not using GTD doesn't affect my productivity as much as it does my stress levels.

Are there people out there who managed to stick to a productivity method for a significant amount of time (years)? If so, which one and what's your secret? Should I keep trying or go with the flow and handle things the way it comes naturally to me?