Quote Originally Posted by Stanelis View Post
Just focus your sight on the mobs you re tanking (looking straight down is a good idea even if you don't have motion sickness anyway), your action bars (to know if your CD are available) and the small aggro interface on the left of your screen (to know when the next set of mobs will spawn) and you should be fine.
Sometimes motion sickness is a simplified term for a problem that is more psychological.

http://www.medicalnewstoday.com/articles/176198.php
"About 33% of people are susceptible to motion sickness even in mild circumstances such as being on a boat in calm water, although nearly 66% of people are susceptible in more severe conditions. "