Like some have already mentioned I think it's a mental thing. I used to get sick all the time sitting in the backseat while doing initial CFI training while my buddy learned how to teach various maneuvers. I used to think to myself "how many damn turns around a point must we do?"

While I never actually puked, I came damn close a few times. The hot and cold flashes... The sweating... and the feeling you can't escape it are the absolute worst.

Everyone is different, but one trick that worked for me was eating a small portion of whatever before the flight. A small bag of chips, an apple, etc. Chewing gum also helped. I tried the ginger pills - didn't help. Eventually I got used to it - until the spin training. The reason I said it's a mental thing is because that once I became a full-time CFI, and had a job to do, I focused on my job and never got airsick again. I never worried about it after that.

Perhaps if you thought of training as more of a job you have to do, and didn't worry about the airsick thing, you may get over it quicker... But you will get over it eventually.