The skill of shipping projects.

It's not complicated:

1. Deciding whether the project is worth getting done or not.
2. Figuring out what done looks like, what's the good enough version.
3. Assigning the resources (time, energy, money) that will help you get to done.
4. Getting to done.
5. Figuring out the next project.

Of course, resistance, perfectionism, self-doubt and even external challenges would stop or delay us at every step.

I can't think of a more important skill that we can build through practice.