i did it out of self hatred, you may have to find your trigger.
but people have stopped by using an elastic band hurts like hell if you do it enough.
putting all your cutting implements in a small box covered in pictures of all those that you love, so that you have to look at all those that care about you before opening the box .
also finding the inner child inside you, we all have one when we were pure and innocent ,and when you are about to cut you think of this inner child and see them in your mind, and ask the question "would you cut this innocent child ?".
also hypnotherapy can help to change peoples mind sets.
take care