Turning off motion blur and other high end graphic effects can really help, especially if they are hurting your framerate

I find if I'm getting a consistent framerate then the effects don't bother me as much, but motion blur plus a sudden framerate drop is guaranteed to make me nauseous

My wife on the other hand cannot handle motion blur effects at all, and any time we play a game together I turn it off immediately

Depends on the game, but usually turning up the FOV to much higher than most defaults will help a lot. But screen size, etc. will have an impact as well.

Exposure therapy. Just play for a very short amount of time, even 2-3 minutes, then stop for a while. Do this over and over. Always keep the duration below the threshold of your motion sickness. Eventually your brain gets used to playing without being sick and you'll be able to play for longer and longer periods. Always stop the moment you feel motion sick in any way - don't try to push through as doing that makes it worse. This is what I had to do to get used to games in VR, and it worked great. I can now play for hours without issue.

FWIW, I've tried everything suggested in the replies to you so far, and nothing's worked. I've just given up trying to play any first-person POV games, sadly.

Exposure therapy helps for me. If I dont play video games for a long period of time I'm always a lot more nauseous coming back. But easing into it over time helps.

I find that a smaller monitor, further away, and on lower graphics settings helps.

If you limit your brain's exposure to visual information, it's less likely to get confused.