If your violence is organised and has a purpose, then you may not wish to change. But if the violence does not get what you want, or you find you get hurt more than others, then you may want to stop.

Also understanding how it feels to be on the receiving end of violence may make you think about stopping.
If you get violent as an emotional outburst, and find you can't control your anger (whether directed onto other things, or turned on yourself), then you may find the download helpful.

The key parts on anger management are:

Recognising when you are getting angry (physical symptoms)

Knowing what makes you angry, the triggers

Knowing what thoughts go through your head and changing them

Having a plan when you get angry, (also others having a plan)

Using relaxation, distraction at the right time (before you get too angry)

Using self-talk to calm down

Using humour, (don't put people down but use it to calm the situation down!)

Think what will happen to you, and others when you get angry

You may want to try out these
self assessment
Bullying others, what its like
Your mood

Dealing with the law (rizer)