This is not possible once someone gets addicted, and it should be done when the person is starting to gamble. Still, some would only get into other activities to reduce gambling if they realize that gambling can be dangerous for them soon if they don't keep themselves away from it or at least reduce their activities in it.

Many people realize their mistake when it's already late, when you are already addicted to gambling, you can't get into other activities because the urge would be too strong to allow you to do that. This is the reason why gamblers need to have an interest in other activities such as sports, video games, or anything in general that can keep them away from gambling as much as possible.

Gambling isn't a bad thing but only if it's done within limits.