Any kid who grew up below average size and stood up for himself was bullied. In grade school I was young for my class and didn't take crap from anyone, including upperclassmen. It was very easy to outwit these bullies and by using my smarts and speed I dished out way more then I got.
I had this older kid chase me home from 4th grade one time- he was twice my size. It had rained the day before so I used that bit of knowledge against him. I would slow down a bit to let him catch up then speed ahead, and I ran him long enough to wind him real good. I had him follow me real close through a side yard straight at a thorn bush, then turned hard right before it, sending him sliding in the wet grass straight into it, face first. I got about ten feet away and laughed at him, all bloody and sucking wind.