The Mental Illness of Persistence

From an article about New Yorker editor David Remnick (by Nicholson Baker):

"Remnick is modest about these writing successes, which he attributes chiefly to 'sitzfleisch' – the capacity to sit in a chair until the work is done. 'A lot of what I do is just the mental illness of persistence,' he told me."

I need to work on my sitzfleisch.