WWhile some people count sheep to go to sleep, Arya Stark recites the names of all those who have offended her. The goal, in case you haven't already worked, is literally strike those names.
During the show, Arya received training from some of the best in the industry, and all of this helped her on the road to becoming Westeros' most ruthless assassin. In the first place, Syrio Forel taught her the art of sword fighting as a good Braavosi, then he learned to defend himself in the ruthless real world of the Hound. More recently, Arya returned from the House of Black and White, where she learned the art of disguise from the enigmatic Faceless Men.