Everybody gets told to write about what they know. The trouble with many of us is that at the earlier stages of life we think we know everything- or to put it more usefully, we are often unaware of the scope and structure of our ignorance.
Loneliness sometimes gives me a quantity of creativeness - you're drinking another glass of wine and you're feeling even worse. Art doesn't work without pain; art also exists for compensating pain.
The thing about a story is that you dream it as you tell it, hoping that others might then dream along with you, and in this way memory and imagination and language combine to make spirits in the head. There is the illusion of aliveness.