Write, not to have written, but to be writing. Write because, inside the moment you are writing, you are in love with the moment of the act of writing. In fact, if you are a mathematician, approach your problems with the same desire. Love the moment of the complexity of the problem. Make the moment tremble with wanting. If you do this, you can never be disappointed, because you are writing out of a love for writing, not out of a desire to be seen as a writer.