I've spent a lot of time on the Great Lakes, inland seas like the Chesapeake Bay and Mediterranean, and the Seven Seas. I probably started before I was 5 y.o. on Lake Superior. Also six years in the U.S. Navy and a lot of hours in my teens and 20s in small private aircraft. I'm probably fortunate because my inner ears became accustomed to such motion as a very young kid.
From my experience, most people do not have a problem until things get really rough. Even then, if precautions like Dramamine, or the newer patches are used, most people don't have problems.
As said in an above post -- no, or very minimal alcohol the night before, and a non-greasy light breakfast.
Take soda crackers with you to munch on. Stay outside and look at the horizon.
Whatever you do, if you feel like you might be getting sick, don't go below decks. It will only make it worse, and you will pay a heavy monetary price for any cleanup. That is what the deck railings are for.
I sure wouldn't worry about it on Lake Michigan in June. Unless a typhoon descends from Canada, the chances of heavy weather at that time of year are fairly slim.
If you don't get motion sickness in a car, on a commercial airplane, or in a kayak going down a river with lots of rapids, you will only have a problem if you let your brain say you should think about getting sick. Think -- "out of mind, out of sight".
