The more turbulence the better for me, it's like launching a 4x4 down a bumpy road IMO, but if you are not used to it, you can get sick for sure. What I've found is that with more exposure, it gets better. The first times I did spins I started getting sick towards the end (never threw up though, but knew when I was DONE). When I started teaching them, the more I did, the more comfortable I got to the point I could do them until the other person couldn't take any more, same with most aerobatics. This makes me think this can be "learned" and is more mind-over-matter. Lots of classic advice about "don't eat anything" is pretty bad, but some people's diets are also pretty bad and set people up for failure.

Summer time at low altitude in extremely hot weather over rough terrain is usually about the worst, it's just sustained beating, but I kinda like it.