It’s difficult for me to read in the car (though not as bad as it was when I was a kid).
I used to take the L to work in downtown Chicago, and would usually read on the train. There would typically be one or two instances a month when the ride was just too bouncy and stop-start for me to read comfortably – I’d start to feel queasy, and have to set my book or magazine aside.
So, “Sometimes”. 
Not really.
This is true for me almost all the time, but there is one windy road over in VT where I make myself sick even as the driver. :smack:
I get motion sickness on boats really easily. But I love to scuba dive, so I don’t avoid it.
Basically never. I’ve never been seasick or airsick, despite having worked on small islands off New Zealand for three years, and doing aerial surveys in small planes that required lots of circling and fast maneuvering low over the ground.
The closest I’ve come was when we were motoring along in 10 foot swells and one of my field assistants upchucked down in the hold. It was raining so hard we couldn’t open the windows so the cabin became permeated with puke fumes. I admit to getting a little queasy then.
I start to feel sick if I read for more than a minute or so in the car, but if I don’t do that, I’m usually fine. Never had a problem on planes or boats.
I frequently get motion-sick on the DC Metro, though. Usually it’s just mild nausea that comes and goes, but a few times it’s gotten so bad that I’ve had to get off and sit in the station for a few minutes before catching another train. And I can’t ride backwards at all. I’d much rather stand. I’ve ridden trains in Boston, LA, Montreal, Minneapolis, Shanghai, Beijing, and Vienna and never had this problem anywhere else, so I don’t know what it is. And I don’t have any issues on Amtrak.
Very easily.
Oddly enough, I have a free hundred hours flying in a helicopter. I was totally fine. I sit in the backseat or look at my phone while in the car then I’m done for the rest of the day.
I never had an issues with motion sickness until I was around 30. Now I can’t sit in the backseat of a car, watch 3-D movies or those ‘found footage’ atrocities, and the slightest dizziness brings on the wretched retches. I don’t usually have problems in a boat. I was seasick once, but I had stupidly lay down on the bow while we were trawling and the boat was up and down and up and down…I fell asleep and woke up so sick. Jumped in the water for a few minutes and was fine.
I can’t read in the car, but I can knit and crochet. I think I must look up more than down, since I knit a lot while watching tv.
More often as I’ve gotten older. I used to love carnival rides, but taking my five year old on the Tilt A Whirl did me in for quite a while. I found a nice spot on a hill and had to lie down and hope I would die. No more Ferris Wheels, or really any rides. Luckily as I’ve gotten older I have found I don’t enjoy carnivals, so the rides aren’t a problem.
Bumpy roads and boats are a problem. My doctor said something about inner ear changes as I’ve gotten older, so maybe that’s it.
Never.
I’m a little the other way round, if anything. When I was younger, I never got car sick, would read for hours on long journeys, loved bumpy ferry crossings etc etc. Now I’m in my mid-thirties and while I’ve never been travel sick as such, I definitely feel less brilliant on bumpy crossings etc.
Edit: My experience is a bit the same as Pai325. I took my two-year-old daughter on the merry-go-round at the local park the other week and felt really rough for about half an hour afterwards 
(OK, we were trying to spin as fast as possible, but still…)
I should add that I haven’t barfed for any reason in at least 20 years, so I guess I’m not a sicky person.
As a child I had a near-terminal case of it. One summer (3.5 mos) of backseat traveling in Canada with the grandparents literally burned it out of me.
I never get motion-sickness at all today - even in rough water.
Had a girlfriend who was prone to motion sickness in car, but didn’t have any trouble at all as a passenger on my motorcycle; go figure.
The first time my wife ever flew was on a flight from Japan to Seattle. She had no idea she was prone to motion sickness until about a half-hour into that flight; she said the remaining 9.5 hours was agonizing.
Hurk.
Dramamine original formula works great for me, so I can go on small boats and car rides with my evil relatives and buses and cruises. Once I forgot to have it on me when we took a New York ferry. Hell.
Never got it, never understood it.
I get motion sick a lot. I have to sit in the front seat or drive. Open air, stable boats are fine, but closed-in boats (such as big cruiseliners) make me terrible sick. I’m fine snorkeling, until I lift my head out of the water and look at the horizon. The waves going up and down make me want to barf.
My husband had an Cadillac that was like riding a magic carpet. I couldn’t even sit in without feeling nauseated.
I hate it. It really does cramp my style.
I have only gotten motion sick a very few times.
The first, I was in the back seat reading; I had just eaten a Hardee’s Ultimate omelet biscuit breakfast, and it was greasier than usual. My dad was driving and he was pissed off about something or other; we were on a day trip, driving little twisty rural roads, very hilly, and he was pretty much driving like an idiot, too fast and taking the turns erratically. I didn’t barf, but came close.
The only other times I have gotten motion sick was when I was taking a really high-powered antibiotic for pleurisy. Miserable.