I really hate being nauseous. There are worse things in life, but not too many of them.
There's a hill ( 3rd Ave going up the north side of Queen Anne ) that I thought I would puke on the sidewalk after climbing, once, a few years ago. I avoided it for a long time after that, searching for the mythical easy way up the hill. There is none. I found other routes that make you climb longer, mostly with a gentler grade, and a few blocks at 18 % thrown in to keep you on your toes. Eventually, as I spent more and more time on the bike, I got to the point where it wasn't that hard. It takes a lot of energy, and slows me down, but it doesn't feel like a punch to the stomach. So I do it a lot more often. Now, for the record, I hit 40 mph going down this hill and that's feathering the brakes a little.