I was a slight kid and didn’t measure up to a lot of the other more “manly” 1st Graders, but I was never bullied.
I think I got an early reputation when I knocked the front tooth out of a kid who kept stealing the candy bar out of my lunch box.
That’s definitely what it takes. If you can physically hurt somebody, who is trying to bully you, do it.
Especially in the early grades. There seems to be some correlation to not being bullied and putting the hurt on somebody before puberty sets in.
The worst bullying I got was in HS. It took me years to de program what those people did to me