[LeonB]

This sent me down a rabbit hole looking for the difference between inertia and momentum. Which showed me, above all, that the people who write dictionaries aren't qualified to write about terms from physics.

I also see that effort it takes to get started on a thing as similar to "excitation energy" in chemistry -- that discrete amount of energy, below which, the system will not change, and above which, bam! it all happens!

By understanding the "next action" you're lowering the "excitation energy" requirement. But that's not a great metaphor to use with the general public. This is why James Clear writes the books, and I just writes the comments.