You learn to write by writing. It’s a truism, but what makes it a truism is that it’s true. The only way to learn to write is to force yourself to produce a certain number of words on a regular basis.

– William Zinsser, from “On Writing”, p.49.

Is there anything you could switch writing with in this quotation and have it no longer be true?  Is there any other way to learn than by doing?