For those who have suffered with motion sickness in VR, it's by no means uncommon to experience, but for many people, small repeated sessions will help you build up your 'VR legs' and you can overcome it.
The key is to stop the moment it starts to feel off and take a break, trying to push through it makes it worse and sets you back. With repeated exposure you should find you can go longer before the sickness feeling comes in, or equally you can tolerate more movement in game without it triggering you.
It isn't an option in all games, but if there is a 'lock to horizon' option in Assetto Corsa for example, that is both far more immersive and far easier to tolerate. It's very hard to describe, but it means when suddenly going up hill say (which would trigger a bit of a 'bleurgh' feeling for me even after weeks of playing), with that lock to horizon on the car sort of rotates up around you (instead of your viewpoint being forced upwards fixed to the car), and then your brain naturally compensates and follows the movement.
It means that your brain stays more naturally 'in control' of its viewpoint and orientation, and so stops it triggering the "oh crap, we've been poisoned, feel sick" response that happens when it feels that its getting conflicting information from its senses.