The hard part isn't necessarily the typing, though that is a labor like any other, it's that everything you write, you at least for a moment live through. Moments of great power, good or bad, can leave you overwhelmed - you mentioned that you are a musician, yes? Have you experienced a closer connection to a piece of music through playing it, through channeling it through yourself, than you would have by merely listening to it?

The author's work is the same. Some authors write fluff with no great effect on the reader, or themselves. While this is honorable, some authors sit at their typewriters and bleed.

Of course, the manly thing is to bleed three thousand words rather than five hundred.