I am not a believer in the “one cool trick” school of personal growth. Articles proclaiming to have one simple trick that will make it easier to manage your money, eat healthy, or improve your productivity may garner a lot of clicks, but they rarely produce much in the way of meaningful progress.

In an earlier post, Productivity Takes Work, I noted that real personal growth takes some serious work — in which you analyze your own behavior to determine what your problem actually is, choose steps to improve it, and then work at those methods until they become habit. And yet, in this column, I am going to present a method that genuinely could be called “one cool trick to improve your productivity.” Consider it the exception that proves my “there is no such thing as one cool trick” rule.

My trick is deceptively simple: Limit the number of things you have “in flight” at any given moment.

I could shore up my argument by talking about the cost of context switching or about limited cognitive resources, but to be honest, I haven’t done a lot of research into why this trick works. I just know that it does. I have seen a wide range of people try it, and it has helped all of us. I say “us” because I use this method, too. In fact, it produced the biggest gain in my own personal productivity since the initial boost I got when I started paying attention to productivity and limiting my work hours.

I discovered the idea via Kanban, a method of managing technical work that evolved out of Toyota’s legendary factory-improvement process. In Kanban methods, you map your workflow and identify the stages through which each task progresses, then limit the amount of “work in progress” allowed in each stage. That is called a “WIP limit,” and it is used to ensure that work is pulled into the later stages rather than pushed from the earlier stages.

I came across Kanban in a former job, when I was looking for help in managing the workload of a team I was leading. I had an excellent team at this company, with people who performed well individually and as a group, but we were struggling to handle the influx of new project ideas. Some team members were almost paralyzed by the competing priorities. Others were working really hard — but not always on the thing that should have been a top priority, which sometimes introduced delays in other people’s work. All of us were less efficient than we could have been.

As I searched for ways to solve the problem, I had a proverbial light bulb moment when I came upon a post by a software team leader named Pawel Brodzinski on using Kanban for portfolio management. As I read more about his ideas, I was intrigued by the idea of limiting work in progress. The Kanban-based method would provide a natural gatekeeping mechanism, so that we could tame the flow of incoming ideas and projects.

When a new project idea came in, we would first decide if it was a good and worthwhile thing to do, and then either consciously put it aside until we had capacity to work on it or set aside some other project to make room for the new one. Instead of viewing our work as one giant to-do list, we could split the load up into phases, and limit the number of projects that could be in any one phase. That is classic Kanban management.

I also thought that we should limit the number of projects any one person could be assigned to at one time. After all, I had been prompted to go looking for new management tools by seeing the people on my team showing symptoms of overload. I am far from the only person to try using kanban methods on an individual basis — check out the personal Kanban site for more — but I didn’t know that at the time, and devised my own system for limiting overload using a physical kanban board and actual magnet avatars for each team member. I made a limited number of avatars, and when we were out of avatars for someone, that was an indication that we shouldn’t assign more work to that person.

Before I tried this on my team, I tried it on myself. I made myself a simple kanban board in an Excel spreadsheet, with just three columns — To Do, Doing, and Done. I populated it with what I call “medium level” tasks — i.e., not multi-month projects (e.g., “write a book”) or fine-grained tasks (e.g., “call the editor”), but things that would take a few days to a few weeks to accomplish (e.g., “draft chapter 2”). I later added a “Prioritized” column to indicate what I thought I would be working on next. I experimented a bit and determined that I work best when the number of items in my “Doing” column was about five. In Kanban jargon, that means my personal “WIP limit” is five.

That number will seem high to some people, but I’ve always been the sort of person who likes to have a lot of things going at once. Still, there is a difference between having a lot of active projects and constantly switching among them. I like a lot of things in flight, but I tend to focus for large chunks of time on one project, come to a natural break point, and then switch to something else. Just like everyone else, I don’t get a lot done if I’m bouncing from project to project over short intervals of time.

Even with my relatively high tolerance for having simultaneous projects in process, I can get overloaded. When I do, I become panicky, and flit from project to project, instead of focusing and doing solid work on any one of them. Since discovering the power of the WIP limit, I now recognize those symptoms as a sign. It means I need to consciously offload some projects — move something back to the “Prioritized” column or over to the “Parked” column I have on the latest iteration of my Kanban board, which I keep in Trello.

Once I’d convinced myself of the value of limiting the number of projects in progress for individuals, and not just for the team, I rolled out my new management method. Team members liked it, and we used it happily until I left that job. Different people had different WIP limits. Some people could only handle two projects at once; most people seemed to have an optimal limit of three. Even after I left, and a different manager with different methods took over, some of my former team members continued to use a personal Kanban board to help stave off overload.

It doesn’t really matter what your personal WIP limit is. People who can manage five projects at once don’t necessarily get more done overall — we just tend to advance more projects in parallel. Meanwhile, people with lower WIP limits tend to use a more serial work mode. Both modes of work are valid, and can result in high productivity.

What matters is recognizing your limit, and developing a system to keep the number of projects you have in progress at or below that limit. That’s the “one cool trick” that can make you more productive. Instead of flailing away miserably at an overflowing to-do list, take a step back, decide which projects are your top priorities, set the others aside temporarily, and dig in to focus on getting things done.

Author Bio: Melanie Nelson is a consultant focusing on scientific information management and project management. She has a Ph.D. in the biosciences from the Scripps Research Institute, and more than 10 years\’ experience managing projects and people.