I’ve noticed that if I say “I won’t do this anymore at all”, it doesn’t work. But if I say “I’ll only spend this much this month on sex workers, gambling, etc.” I’m able to mellow down. I’ve also noticed some people suggest that moderation doesn’t work and you should try to be as cold turkey as possible.
I think that depends a lot on the specific addictions and which circumstances make you want to give into it more. e.g. physical addictions like to highly addictive drugs are typically harder to moderate that non-physical addictions.