Ginger helps. Buy yourself a packet of Ginger Nuts and nibble away at one or two. Try eating one before playing, then after about 20-30 minutes, or at the first sign of discomfort, take a break and nibble another. I've found any kind of discomfort clears up within about 5-10 minutes and then I can just continue on with no bother. Playing this way isn't necessarily bad. You can stretch the experience out over a week or so, instead of days as it would normally take.
There's a number of reasons for motion sickness, but the main ones are always latency issues, or frames. The way PSVR works, it interpolates frames, so some games aren't true 120fps. Another is tracking, but then thats directly related to latency also, and the PSVR's tracking solution is sketchy at best. It works, but there will be issues with it. Try playing in a room as dark as possible, and also calibrate the headset. Saying all that, I used to get motion sick when playing certain FPS games, so it's not something that's entirely exclusive to VR either, but there's a certain adjustment to be made for it. I'm someone who gets sick just from car trips sometimes, but only in certain cars, in certain situations. It varies, and VR will be exactly the same.
