If you want to learn how to play baseball, you should start throwing balls at least.

Watching it is good if you can't or don't have time to do it.

Out in the field, it's also important to learn what kind of moves you make in baseball.

Playing the catch, hitting balls with a baseball bat, and recognizing what are there, you are getting ready to play.

Rules?

You can learn it while playing.

If it's not enough then, you can learn it from someone or something now and then.

I don't think it's not that different from learning a language, I guess.

What are you doing there?

Studying it from textbooks to be fluent?

Reading books all the time so that you can get more vocabulary?

Aren't you too scared to do what you are supposed to do in reality?