How can I support my boyfriend with him stopping watching porn?

I have never had a problem with porn or him watching it but he came to me and said that he thinks he has an issue with watching it too much (it has never effected our sex life and we have been together 7 years) and asked for my help to help him stop. I want to be there for him because he wants to stop. Has anyone ever been through this and how can I be supportive for him? Thank you!