It's also the worse thing about being a writer. (I have to be my own accountant, booking agent, and make myself write.)
I first felt guilty if I was not writing 90% of the time .. I now realise over the life of a book or article i'm working on, the writing is only 25% of the time. the rest of the time I'm thinking, correcting, checking the names of places, sorting photos, traveling, taking notes and all the rest!