There is only one way: Go within. Search for the cause, find the impetus that bids you write. Put it to this test: Does it stretch out its roots in the deepest place of your heart? Can you avow that you would die if you were forbidden to write? Above all, in the most silent hour of your night, ask yourself this: Must I write? Dig deep into yourself for a true answer. And if it should ring its assent, if you can confidently meet this serious question with a simple, I must, then build your life upon it. It has become your necessity. Your life, in even the most mundane and least significant hour, must become a sign, a testimony to this urge.
So don't be frightened, dear friend, if a sadness confronts you larger than any you have ever known, casting its shadow over all you do. You must think that something is happening within you, and remember that life has not forgotten you; it holds you in its hand and will not let you fall. Why would you want to exclude from your life any uneasiness, any pain, any depression, since you don't know what work they are accomplishing within you?
This, above all, ask yourself in the stillest hour of the night: must I write? Delve deep into yourself. And if this should be affirmative, if you may meet this question witha strong and simple 'I must' then build your lfie according to this necessity; your life even into its most indifferent and slightest hour must be a sign of this urge and a testimony to it.