Most people can reportedly get used to the discrepancy between the vision and balance senses and be rid of the motion sickness (with some training: keep playing until you start feeling uncomfortable, wait until the next day, go again).

Ginger can also help delay onset.

It can also be noted that motion sickness really only is a problem where the game character moves while you stand still physically (e.g. using a joystick to move around). Other forms of locomotion (like teleportation) are usually fine.