There's an Ernest Hemingway quote I found scrawled in an old notebook – "It's none of their business that you have to learn to write. Let them think you were born that way."
There's always some reminder to bring you back to the fact that writing is a craft. It must be worked over with sweat and effort. It's probably more obvious in other crafts like woodwork or glass blowing where the sweat is actual perspiration, the effort more physical. But always remember writing is a craft and it has to be worked at that same way.
As Hemingway also said, the first draft of everything is shit. It's the working over it with craft that makes it resemble the inspiration that caused the whole deal. Joyce reportedly wrote only a few sentences a day, and somehow still ended up with Ulysses.
When you achieve that final piece you're after then it will look easy. That's the craft. Let them think it was.