Sometimes it’shard to sit and write for half an hour. Sometimes it’s hard to stop writing after six hours. Sometimes I go a week without writing. Sometimes I go to bed thinking about my books and wake up motivated to get back to work.

Does this happen to you with your hobbies?

During the summer (less teaching!), I like to think I’m going to write for hours every day. This author thing is my summer job, right? Alas, it’s more sporadic than that. There are weddings and hikes and family visits a...