Compartmentalize: Manage Your Brain.
Write what you’re writing when you’re writing it. Your subconscious mind will keep “working” on your current projects when you’re working your day job, or are picking the kids up from school. It’s impossible to write commercially until you learn to compartmentalize. Over time, this becomes natural. You think about a client project, or your series of short stories when it’s time to write; you forget about them, at least consciously, the rest of the time.
We’ve discussed strategies like free writing and getting a timer before. They help you to compartmentalize.