I would work to just "don't" do it. Not wanting to feel pain is not all that is part of consciousness. Somewhere you know whatever might hurt you and just "don't care." Start caring if you want to stop. Work to respond to the "that might hurt me" signal you're getting but not paying any attention to. It might take some time, we don't change behaviors right away. Start by taking good care of yourself after you do something that hurts you; show yourself you value yourself. That you can consciously choose to do. Eventually you'll get closer and closer to not letting hurtful things happen until you are able to respond in the moment. The more you take care of yourself the more your "automatic" self will follow that lead.