To prevent motion sickness (seasick, carsick, or airsick), use pressure on both wrists. Pressure can easily be obtained with a wristband, like Sea-Band. Apply the wristband the width of two fingers below the crease on the inside of the wrist. For emergency use, use several rubber bands together, or by pressing with your thumb (which is hard to do on both wrists at once, but pressure on one wrist is better than none). In an emergency, you can use a thick rubber band, but it should be large enough so that you should not feel numbness or see any color change in your hands.
If you are already seasick, this pressure method will stop the nausea, but it is so much better to prevent it in the first place.
When riding in a car, people in the front seat almost never get carsick. Those in the back seat who are prone to getting carsick are better off if they look through the front window instead of the side window. They should also never read in the car. Letting in some fresh air helps. Sleeping in the car keeps your eyes and ears from getting confused about the motion.
Find several objects in the car that you can focus on (left visor, radio, right visor, left handle, right handle). If you start to feel sick, keep your head still and look at these items one by one, quickly, over and over for about 30 seconds.
Dramamine does work, but it is not great to drug little kids, and it makes kids and adults pretty sleepy. Pregnant women should not take pills, and people already on medication may not be able to add Dramamine.
Feeling carsick, seasick or airsick is not "all in your mind." Animals also get sick. It has to do with what the inner ear feels and the eyes see not jiving.