For a gambler that have got himself seriously addicted to gambling, asking him to give up gambling is not an easy task, no one can really help him except himself, maybe he needs to find another hobby to keep himself busy so he won't kept thinking about gambling in his mind all the time.
This isn't only true for gambling. Anybody who has done one thing extensively for a long time will have trouble getting out of that habit, no matter what habit it is.
Habits are leading into addictions, that is right. Part of gambling addiction is cause gamblers are not admitting their mistakes, they don`t accept loss, they want to redeem and win it all back. Gambling addictions are one of the strongest addictions, worst then drugs, cause you can clean your body from drugs but how to clean a mind and force him to not think about gambling? I saw pills for gambling addiction, but I wouldn`t recommend that to anyone, that is just replacing one addiction with another one, where can lead that?
Fight against gambling addiction is hard, there is no other cure that courage not to gamble, day by day until you make it to the week, month..and like that until the end of the life, cause gambling addiction can never be cured, but it can be restraint.