Navasha already pointed it out what it took me a long time to figure out: FOV is a big deal.
I first noticed it with Half Life. I'd play 30-45 minutes, and I'd have a horrible headache and nausea. There was all this hype around the game, but I couldn't play it. I tried in 30-45 minutes bursts, but it just wasn't worth it. But hey it's a shooter. So whatever. Then came Morrowind. I was a big fan of Elder Scrolls: Arena. It was one of my first PC games. I played it to death. I missed out on Daggerfall as I wasn't playing games much while it released. But Morrowind I was hyped for. This was actually first time I ever noticed a CRPG not having bad graphics upon release. And then I couldn't play the thing--like couldn't get out of the first town. Fighting mudcrabs, watching the High Elf walk around with a torch at night: I just couldn't play the game for terrible nausea and headache again. That killed me. I wanted to play that game.
Fast forward a few years. I decide to play Morrowind again. Maybe the speed of new hardware will make it smoother or something. Nope. 30-45 minutes, and I'm sick again. Ugh. Then I research it. FPS Optimizer. It has an FOV setting. I crank it to 90, and I can play the game for hours without issue. So that's it: it's FOV. Doesn't matter if I play it in first person or third person. If I crank that FOV up, I'm fine. Sure I notice it more with first person games, but so far I've been able to fix it with FOV regardless.
I figure I'm done with these problems. Though lurking in the back of my mind are games you can't modify. I really wish developers appreciated what a dealbreaker no FOV control can be for people and do something about it, plan for it. Maybe they do appreciate it. But I wish they would all action that.
I get Last of Us. I liked Uncharted. And i generally like misery in a narrative. So I'm up for it. 30-45 minutes, and I feel terrible. Crap. Then I try something. I moved my couch as far from my TV as I could: like 9' from a 42" screen. And I'm able to play the game without issues. So that's a different kind of FOV slider: sit farther from the screen. So at least I have that.
Not everyone is the same. Maybe not all motion sickness is FOV. But it sure was the main culprit in my case. So if you have motion sickness in gaming it's worth trying out 1) FOV sliders if they're available and 2) sitting further from your screen, if possible (and maybe that's pushing your monitor to the back of your desk or moving your chair/couch farther from your TV).
Article on Implementing FOV Slider in Borderlands 2