What happens is that it become a habit and habits are incredibly difficult to overcome, since the moment someone gets used to do something then they have problems imagining what else to do with their time if they are not engaging in that habit, so once gambling becomes a part of your daily routine then it can be very difficult to stop it, as even without thinking about it a person may find themselves gambling when they had no intention to do so, and as you say the only way to avoid this is by actively occupying their minds so they do not think about it anymore.
Good point, if you will keep occupying your mindsets and keep yourself busy with your love ones or with your friends, people who are not engaged to any gambling related activities, it will be easier to cope up and lessen the chance of the temptation in bringing yourself inside any gambling activities. It's more about how serious you are in moving or quitting away from this business.
Once you figure it out, your system will comply and you will start to stay out of any gambling participation.