When I did plays in high school and college, I never remember memorizing my lines, but once I had blocking, I had all my lines memorized. Once I had movement associated with words, it was fine. Before I had blocking, it was just text on a page. Once it became embodied, it was much easier.
How can you defy fear? Fear is a human instinct, just like hunger. Whether you like it or not, you become hungry. Similarly with fear. But I have learned to train myself to live with this fear.

