I sometimes go to the sidelines of marathons and punch random marathoners in the nuts
Why are you punching marathon runners?
I just do it because I have this urge to do so
You shouldn't intentionally try to hurt other people. You could start a big fight and get into a lot of trouble.
Yeah, but those marathons have it coming.
What did they do to deserve that? If you have some anger towards runners, why is that. It is better to seek help for the cause of the problem, than lashing out and hurting others.