"... play games for a living only if you are VERY, VERY good at it..." - quote from dude Fatal1ty

Play-testers (test games for a living) is said to be a nightmare. Play certain sections of the game AGAIN and AGAIN and AGAIN... Also, for those who are timed, you constantly do a certain level of the game in a timely manner again and again... and they will keep track of your performance and take into consideration of the final game design time.