Knowledge vs Skill

I'm reading a lot. I'm writing about what I'm reading. I'm thinking about what I'm reading and then writing about it. It's the most active reading I've ever done.

I can explain TDD by saying:

I don't think I have the skill of TDD. To have the skill would mean being able to perform it well in any situation, adapting the rules if necessary. Building the skill requires practice. I practice it here and there at work. I don't really do it in a systematic way with measurable results. I don't quite know how I would measure it.

TDD requires fast tests in order to be practiced effectively. I do not have fast tests where I work right now. I do not have the skill to make the tests faster. I can't effectively practice TDD with these slow tests. Now I need the skill of writing fast tests.

More and more I'm coming to the realization that there's more to it than knowing about Red/Green/Refactor. I don't think I'll be able to find out what those things are unless I practice. And I won't be able to just practice using toy exercises. I'll have to practice using production or production-like systems.