Is there a way for gamers who get motion sick easily to play their favorite games without feeling sick.

In the last year I have finished building my first PC and got a nice monitor but I found that it's very difficult to play first person games without getting motion sick. I have tried turning down mouse sensitivity in my games and even just playing slower but it just isn't work. It sucks that I buy these games and can't play them. Does anyone else have this problem and have you found ways to fix it? Are there mods I could get? And what if a game doesn't have a third person mod?