Damien

First off you should do selfless acts that harm you, but not that much that you can't handle it, but it should come with losses for you.

In the previous mentioned event, I got a cold which was my loss. 

When you show others that you actually have a loss by their actions, they will rethink it.

Unless they're douchebags, because those guys will throw you down the lake again <,<

xD There are a lot of those people in this world sadly.

That's where you bring in the big guns.

This is where they see that there are consequences for their actions. Maybe not directly from their actions, but a fatal beating has always been a good answer.