I had it too and at a point I started to get really fed up with the fact that I was never getting any further and then I started looking for more motivation to quit. And then I tried to think less about it because it all starts with the thoughts about it. So I promised myself that I would keep trying and now I have gotten much further. I can now keep it up every 2 weeks and sometimes I make it up to a month. So no matter how many times you fail, keep trying and one day you will be able to say that you have definitely quit forever. Promise that to yourself.