I was raised with what at this point in time I guess are somewhat "old fashioned" manners. I'm about as far from religious as you can get, while still being respectful about whatever other people choose. I still say "bless you" if someone sneezes. I hold doors open for people if I get to a door first, doesn't matter the gender of the people who are behind me. I'm short. I'll ask who ever looks like they're not in a rush and is taller if they mind grabbing something for me at the grocery store. I give my seat up on public transportation if someone seems like they need it more than I do, no matter what gender the person is. It's ingrained in my head not to eat until everyone is there to start eating at the same time, put a napkin on my lap, etc.
One of the farther back but blatant times I dealt with sexism that really ticked me off and I still remember is in an art class. The teacher who was also coach of one of the sports teams was interacting with the students. He told the females to clean/tidy the classroom, and he wanted the males to help him throw together some easels for painting. My dad has done woodworking for longer than I've been alive. He does beautiful custom furniture. I'm not a craftsman like him, but I know enough to do basic shit. I knew more than a lot of the snot nosed little assholes he wanted to help him. It was just such a bald faced "I don't expect you silly females to know anything about this because you're females" that I wanted to strangle him.
As someone who is really into video games I run into it some, too. The "oh, are those your boyfriend's video games?" definitely happens. Less than it used to be when I was younger, but it's still a thing.
I'm in some ways harder to offend than I used to be, and in other ways it's easier to get on my nerves. I notice more issues than I used to (I think), but I pick and choose my battles more. I've become more perceptive about when someone is just ignorant and when someone is trying to stir shit/intentionally being a fucker.