The same goes for treating writing like a hobby. Don’t get us wrong: writing as a hobby is fantastic. If you have no desire to publish or make an income but want to express yourself, go ahead and hobby it up. But if you want to build a career as an author, hobby-thought will kill you.
Set yourself a schedule. Personally, I write for four hours every weekday morning starting at 6am. If you have a day job, you might only be able to manage an hour a day, or four hours on the weekends. But whatever your quota, set it, put it on a calendar, and abide by it. Your writing hours should be unchanging and immutable, because this is a business.