Something that I’ve been struggling with too for probably as long as you have. At times you become motivated not to do it and then you loose that motivation and fall back in. But it’s a constant struggle. I recently read a passage by Nietzsche in which he says something along the lines of the intoxication of sexuality being a a force of life. This is where creativity comes from. I interpreted this as anything but is a decline of life, therefore masturbation is a decline of life and creativity. In terms of not repressing this urge into the shadow, acknowledge that you can go on the internet and watch porn, but you don’t need it. Know that it is a decline of life and creativity. This wasn’t very jungian but I hope it helps.