Do be kind to yourself. Fill pages as quickly as possible; double space, or write on every second line. Regard every new page as a small triumph. Until you get to page 50. Then calm down, and start worrying about the quality. Do feel anxiety - it's the job.
For many years, at great cost, I traveled through many countries, saw the high mountains, the oceans. The only things I did not see were the sparkling dewdrops in the grass just outside my door.