Momentum

An object at rest tends to stay at rest and an object in motion tends to stay in motion.
--Newton's First Law of Motion

I doubt Newton had writing in mind when he came up with his First Law, but it can be applied to writing just as easily as it can be applied to physics.

The concept of inertia applies here in both senses of the word. If you are in the dangerous habit of not writing, you'll tend to stay in that habit. Solve this by creating a new writing habit that is reasonable and achievable, like writing for 30 minutes a day, every day.

If you set a goal like this and stick to it for two or three weeks, you'll create a habit based on the "good" form of inertia, which means you're likely to keep writing, maybe for years.

That's not a bad habit to have.