"An object at rest tends to stay at rest, and an object in motion tends to stay in motion." Isaac Newton's First Law of Motion seems to apply as well to projects as it does to physical objects. In my experience it is much easier to continue working on a project and keep it moving if it already has decent momentum. It is much harder to make any progress on a project that is languishing from lack of attention, or has hit a barrier that has stopped it completely. To keep a project that you care about moving, you need to at least maintain momentum, and preferably build it up.
In classical mechanics, the measurement of momentum of an object is a simple calculation consisting of the mass of said object multiplied by its velocity:
The equation couldn't be simpler, but it has powerful implications in physics. Those implications can also apply to projects.
Specifically, a project has properties that could be considered its mass and velocity. The mass of a software project could be the amount of code, design assets, and documentation that have been created for it. If the project has been released and is out in front of real users, the mass could also be the number of people using it. If the users are actually customers paying for the software, the mass could be the amount of revenue the software is bringing in. In any case, the mass of a project is most likely growing over time. Since the mass is increasing, according to the equation, momentum should also be increasing, but there is that other term to consider.
The velocity term is a vector that has a direction and a magnitude. The magnitude of the velocity (a.k.a. the speed) of a project is simply how fast it is moving over time. How quickly are features being added, bugs getting fixed, or interfaces getting polished? How fast are infrastructure and various support mechanisms being added to the project so that it can survive in the wild? Those are some of the things that determine the speed of a project.
As for the direction, that is determined by how the project is progressing towards the goals set out for it. Two things need to be considered here. The project could either be headed in the direction of the project goals or not, and the project goals could either be in the right place or not. Ideally we want the project goals to be in the right place and the project heading towards them, but that's not always reality.
We've now come to the first insight we can gain from this mental model. (It's obvious, but that's the way insights are sometimes.) If you realize a project is heading in the wrong direction or the goals are way off-base, then how easily the project can be course-corrected will depend on its mass and its velocity. The larger a project is or the faster it's moving, the more energy it will take to change its course because it has more momentum. Likewise, the larger the course correction needs to be, the more energy it will take to get it back on track. Small adjustments can be made even to large or fast-moving projects relatively easily, but if you have to turn a large project completely around, it is going to take a lot of effort.
Something else that happens to projects over time, other than needing course corrections, is that they grow. Much of the energy that a team puts into a project gets converted to mass in the form of the aforementioned materials, customers, and revenue. All of this accumulated mass makes projects more sluggish as they grow. It takes more and more energy to keep a growing project moving fast, which is why it seems physically impossible to make progress on huge, crusty projects with any kind of speed. In contrast, a greenfield project has almost zero mass, so it feels like making lightning fast progress takes no effort at all.
Those greenfield projects don't stay small for long, though. A new project that's making good progress will quickly increase in mass. As it grows, another force will come into play that is alluded to in Newton's First Law of Motion—friction. Since a project is never built in a vacuum, it will have to overcome all kinds of friction to stay in motion. As a project grows, its surface area will also grow, increasing the frictional forces on it.
Even projects that you wouldn't think would encounter more friction as they grow will, in fact, do so. For example, this blog seems to be adding friction as I write more and more posts. I didn't anticipate that. As I've learned things about writing and added new features to my later posts, I am acutely aware of the benefits of revisiting some of my older posts and updating them. I should also refresh my memory of things that I've already written. Both of these frictions continue to grow as I write more, and I'm sure other frictions will arise as I keep going. I also continue to deal with the multitude of distractions from everyday life that are pulling me in directions other than writing.
One way that I've found to keep the momentum up with writing—something I committed to from the start—is to write every single week, no excuses. I normally do even better than that by doing something blog related every single day. It's not always writing; I do that two to four nights a week. The rest of the days I'll make notes in Trello when an idea strikes me or I'm reading something and come across a good example for a future post. I also take time to think about my writing. It may not all seem like momentum, but it all adds up to a blog that keeps moving. It has worked pretty well for me.
I've found that that mentality works well for any kind of project, personal or work-related. Personal projects have all kinds of frictions, not the least of which is probably work and the energy drain that comes with it. It's so much easier to come home and veg out in front of the TV or drift on the internet than sit down and work on a project, but none of that will keep the momentum going, even if you care deeply about the project. The same is true for work projects. Frictions abound with meetings, email, and other (sometimes necessary) distractions.
The best way to overcome these frictions, whether for work or personal projects, is to do something for the project every day. It doesn't have to be a big thing every day. Some days are so packed with meetings or you're so exhausted when you get home that the best you can do is fix one simple little bug or think about the next feature for ten minutes, fifteen minutes tops. Do that. Even a small bit of progress will keep the momentum up on a project so that it's still moving when you have the time and energy to do something big for it.
The last thing you want is for the project to stop completely. Then you have to overcome the most devastating of all forces—static friction. Keeping momentum going is so much easier than starting up a project from a dead stop, especially as the project gets bigger (remember the project's mass). If you want a project to keep going, do at least one thing for it every day because the momentum will help carry your project along. Momentum is a powerful thing.